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Workshop Manuel

Volume IA - Engine, 16 valves

DR. ING. h. c. F. PORSCHE Aktiengesellschaft

As webpage by http://www.9ss1.dk/porsche944

944 Table of contents volume I-A

General

Technical data

Maintenance, Self-diagnosis

Fault diagnosis, DEE control unit

Connecting into the vehicle - 944S

Starting fault diagnosis

Functional test - actuator and input signal

List of test codes

System adaptation

Knock detection

Troubleshooting

List of fault codes

Clearing fault memory

Operating conditions for start of diagnosis

Operating instructions for System Tester 9288

Engine, Crankcase

Tightening torques for engine (16-valve)

Tolerances and wear limits

Engine, removing and installing

Engine, Crankshaft drive, Pistons

Notes on assembly for pistons, from Model 87 onward

Checking pistons and cylinder bore

Pistons from Model 89 onward

Installing cover for oil-centrifuge partition

Engine, Cylinder head, Valve drive

Camshaft salling, checking and adjusting

Camshaft salling, checking and adjusting for Model 89 onward

Applying the TOC mark on the camshaft sprocket

Camshafts and cylinder head, removing and installing

Cylinder head, installing and tightening

Camshafts, installing

Camshaft seal, installing

Camshaft specifications

Chain tensioner, removing and installing

Cylinder head, disassembling and assembling

Valve springs, removing and installing with Sauer tool

Page

0.9

03 - 1

03 - 3

03 - 5

03 - 7

03 - 13

03 - 15

03 - 17

03 - 19

03 - 29

03 - 31

03 - 32

03 - 33

10 - 0101

10 - 0102

10 - 101

13 - 101

13 - 102

13 - 103

13 - 105

15 - 101

15 - 104 a

15 - 104 b

15 - 105

15 - 110

15 - 111

15 - 112 a

15 - 112 b

15 - 113

15 - 115

15 - 118

Table of contents

Printed in Germany - XXIV, 1991 1

volume I-A Table of contents 944

Machining mating face, cylinder head

Vaive springs, removing and installing, removing valve stem seal

Valve stem seal, installing

Checking valve guides

Replacing valve guides

Checking valve seat wear limit

Valve seats, checking and machining

Checking and adjusting installation length of valve springs

Engine - Lubrication

Replacing engine oil and oil filter

Pressure-reduclng valve, removing and installing

Engine - Coating

Checking cooling and heating system for leaks

Fuel supply

Replacing fuel filter, checking injection lines for leaks and tightness

Checking delivery rate of fuel pump

Line routing, fuelsystem, M 44.40

Fuel preparation - L-Jetronic/regulation

Replacing air filter cartridge, checking intake-air guide hoses

Testing and adjusting specifications

Checking fuel pressure

Checking idle speed and CO - with catalytic convertor

Checking idle speed and CO - without catalytic convertor

Replacing air filter cartridge for Model 89 onward

Exhaust system

Exhaust system - check tightness of flanges

Ignition system

Equipment table

DEE control unit coding - 944 S, Model 87 onward

Replacing spark plugs

Equipment table, Model 89 onward

DEE control unit coding - 944 S 2, Model 89 onward

DME-Diagnosing / Troubleshooting

Page

15 - 120

15 - 121

15 - 122

15 - 123

15 - 125

15 - 130

15 - 131

15 - 133

17 - 101

17 - 102

19 - 101

20 - 101

20 - 102

20 - 103

24 - 101

24 - 102

24 - 103

24 - 105

24 - 106

24 - 107

26 - 101

28 - 101

28 - 103

28 - 104

28 - 105

28 - 107

D-24/28-1

2 Table of contents

Printed in Germany - XXIV, 1991

944 General

TYPE 944 S (16-VALVE ENGINES) - '87 MODELS ONWARD

Printed in Germany - XIII, 1987 Technical Data 0.9

General 944

TECHNICAL DATA

(Adjustment specifications and wear data are stated in the appropriate Repair Groups)

Note: US values are stated in parentheses

DRIVE UNIT

Internal engine designation

Number of cylinders

Bore

Stroke

Displacement (actual)

Compression ratio

Max. engine output to

80/1269/EC

Net power, SAE J 1349

at engine speed

Max. torque to

80/1269/EC

at engine speed

Net torque, SAE J 1349

Max. spec. power output

Net power, SAE J 1349

Fuel octane rating

Max. perm. engine speed

Engine weight (dry)

ENGINE DESIGN

Type

mm/in.

cc/in.3

kW/PS

kW/HP

rpm

Nm/kpm

rpm

Nm/lbft

kW l/HP l

kW l/HPI

RON/MON

rpm

kg/lbs

M 44/40

4

100/3.94

78.9/3.11

2479/151

10.9 : 1

140/190 - 135/184 Australia

140/188

6000

230/23.5 - 225/22.9 Australia

4300

230/170

56.5/76.6-54.5/74.2 Australia

56.5/75.8

95/85 - 92/82 unleaded Australia

(95/85 premium unleaded)

6840

175/386

4-cylinder, 4-stroke in-line spark ignition

engine with two balance shafts

0.10 Technical Data Printed in Germany

944 General

Crankcase

Crankshaft

Crankshaft bearings

Connecting rods

Connecting rod-bearings

Pistons

Balance shafts

Balance-shaft bearings

Cylinders

Cylinder head

Valve guide

Valve arrangement

Valve timing

Camshaft

Camshaft drive

Balance-shaft drive

Valve clearance

Two-part light alloy crankcase

Forged, 5 bearings

Plain

Cast, opt. sinter-forged

Plain

Light alloy, cast

Forged

Plain bearings with bearing shells

Light alloy

Press-fit, special brass

2 intake, 2 exhaust

overhead V

Two overhead camshafts, hydraulic

bucket tappets

Without bearing shells, carried in

cylinder head

Toothed belt and internal chain

Toothed belt

Self-adjusting (hydraulic)

Timing Intake opens

Intake closes

Exhaust opens

Exhaust closes

4° after TDC

40° after BDC

36° before BDC

4° before TDC

Printed in Germany - XIII, 1987 Technical Data 0.11

General 944

ENGINE COOLING

ENGINE LUBRICATION

Lubrication

Oil pressure

Oil-pressure indicator

Max. oil temperature

Oil consumption

EXHAUST SYSTEM

EMISSION CONTROL

HEATING

n = 5000 rpm

l/1000 km

Sealed cooling system, electric fan

with thermoswitch, antifreeze effective

to - 25°C

Forced-feed lubrication with

sickle-type pump, oil filter and

oil-water heat exchanger in main oil

flow and secondary water flow

integrated in crankcase

Approx. 4 bar, at operating

temperature

Pilot lamp and pressure gage

140°C

Up to 1.5

Standard

2 double-wall manifolds, branch pipe to

primary muffler, 1st and 2nd

secondary mufflers

Option: M298 or M299 and USA and

Australia as standard, catalytic

converter instead af primary muffler

Standard: engine-internal

Option: M298 or M299

and Australia

heated oxygen sensor with 3-way

catalytic converter

Hot-water heating with heat exchanger

and blower

0.12 Technical Data Printed in Germany

944 General

FUEL SYSTEM

Injection

Fuel delivery

Fuel octane rating

Fuel consumption

to 80/1268/EC or

ECE R 15/04

Constant 90 km/h

Constant 120 km/h

EC exhaust urban

cycle

ELECTRICAL SYSTEM

Suppression

Battery voltage

Battery capacity

Alternator (output)

Ignition

Firing sequence

Ignition timing

RON/MON

l/100 km

V

Ah

A/W

DME

Digital Motor Electronics

1 electric fuel pump

Standard:

95/85 - European standard

premium unleaded

possible

Opt./M298:

95/85 unleaded

- European standard premium -

Australia: 91/82 unleaded

Standard:

6.7

8.3

12.5

ECE-R 10 and 72/245/EC

12

50 - optional 63,

sports package 36

115/1610

- sports package: 90/1260

By DME

1-3-4-2

By DME

Printed in Germany - XIII, 1987 Technical Data 0.13

General 944

BODY DESIGNS

Integral all-steel body with front air dam and rear

spoiler

- as coupe, opt.: removable hardtop panel, also

available with fog lamps set in PU front air dam as

optional extra.

DIMENSIONS (at DIN curb weight)

Length

Length with opt.

extra US bumpers

Width

Height

Wheel base (in

design pos.)

Track:

Front

Rear

Ground clearance

(at per. total

weight)

Bed clearance

(at per. total

weight)

Overhang angles:

Front

Rear

mm/in.

4230/165.354

4290/168.90

1735/68.31

1275/50.20

2400/94.49

1477/58.2

1451/57.1

1442

120/4.72

53/2.09

14°

15°

(4290/168.90)

Rim size

7 J x 15

7 J x 16

8 J x 16

7 J x 15

7 J x 16

8 J x 16

9 J x 16

0.14 Technical Data Printed in Germany

944 General

WEIGHTS - to DIN 700 20 -

Curb weight

Front

Rear

Total

Per. axle load

Front

Rear

Per. total

weight

Per. trailer

load

Braked trailer

Unbraked

trailer

Max. car/

trailer weight

Max. drawbar

load

Per. roof load

With genuine

Porsche roof

transport

system

kg/lbs

Standard

640/1411

(650/1433)

640/1411

(650/1433)

1280/2822

730/1609

900/1984

1600/3527

1200/2646

1200

500/1102

500

2760/6085

2760

50/110

50

35/77

75/165

Sports package

630/1389

610/1345

(630/1389)

1240/2734

(1260/2778)

730/1609

(720/1587)

900/1984

1600/3527

(1550/3417)

up to 16% gradient

for Italy

up to 16% gradient

for Italy

up to 100 km/h

Australia,

standard

640/1411

1280/2822

730/1609

920/2028

1620/3571

Printed in Germany - XIII, 1987 Technical Data 0.15

General 944

CAPACITIES

Engine (measurement with dipstick

as per Driver's Manual is definitive)

Engine oil

Engine coolant

Transmission with differential

Fuel tank

Brake-fluid reservoir

Windshield and headlight washing

fluid reservoir

Proprietary HD oils to APl

classification

SE or SF, see Driver's Manual

Approx. 6.0 l

Approx. 8.5 l

Approx. 2.0 l hypoid oil, SAE 80

to MIL-L 2105, APl classification

GL 4

Approx. 80 l, including approx.

8 l reserve

Approx. 0.2 l

Approx. 0.6 l

PERFORMANCE

Maximum speed

Acceleration from

0-100 km/h*

(0-60 mph)*

(1/4 mile

from standing

start)*

Kilometer from standing start*

CLIMBING PERFORMANCE

In % (slip limit)

km/h/mph

s

1st gear

2nd gear

3rd gear

4th gear

5th gear

228/142

7,9

(7.7)

(15.4)

27.8

62%

35.6%

21.5%

13.3%

9.4%

*DIN curb weight and half of payload

0.16 Technical Data Printed in Germany

944 General

Technical data - Type 944 52 - Model 89

(Values for adjustment and wear are to be found in the respective repair groups)

Notes: USA values are given in brackets

Drive unit

Internal engine designation

Bore

Stroke

Displacement (actual)

mm (in.)

cm3(in.3)

Manual transmission M 44.41 (3.0 I)

104 (4.09)

88 (3.46)

2990 (182.5)

Displacement (rounded down) cm3 2969

Compression ratio

Max. engine power

88/195/EEC

Net power, SAE J 1349

at engine speed

Max. torque

88/195 / EEC

(Net torque, SAE J 1349)

at engine speed

Max. output per litre

DIN 70020

(SAE J 1349)

Speed governed by

fuel cut-off

Engine weight (dry)

kW (HP)

rpm

Nm (kpm)

Nm / lbft

rpm

KW/I (HP/I)

rpm

kg

10.9: 1

155 (211)

155 (208)

5800

280 (28.5)

280 (207)

4100

51.8 (70.6)

51.8 (69.6)

6480 +- 20

175

Technical data

Printed in Germany - XIX, 1989 0.17

944 Maintenance, Self-diagnosis 03

DME control unit error diagnosis

DME control unit error diagnosis 944 S

as from 88 model

As from model year 88, the DME control unit

944 S is capable of a self-diagnosis. That is to

say, the control unit is capable of detecting,

storing and displaying system errors. The con-

trol unit capable of diagnosis is identified by

an altered part number. A specially developed

diagnostic tester (special tool No. 9268) is

then used to read out the error memory and

to test specific components and control sig-

nals af the fuel and ignition system.

87/793

Important: Before diagnosis, the battery or

the connector of the DME control unit must

not be disconnected as otherwise the error

memory will be erased.

DME control unit error diagnosis

Printed in Germany - XVI, 1987 03 - 1

03 Maintenance, Self-diagnosis 944

Display

LED off Test sequence terminated / igniti

Flashing LED Error code / test code

LED on Ignition on

03 - 2 DME control unit error diagnosis

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Connection in the 944 S

In the 944 S, the diagnosis socket is

attached

to a separate cable harness located above

the

DME control unit.

87/1012

Ignition off

After connecting the tester, the following dis-

play must appear.

Display:

If this is not the case, check the tester ter-

minals or check the power supply of the

diag-

nosis socket in the car by referring to the cir-

cuit diagram.

Diagnosis socket in the car

Pin 1 = terminal 15

Pin 2 = terminal 31

Pin 5 = terminal 30

Pin 9 = Hall generator

87/908

Connection in the 944 S

Printed in Germany - XVI, 1987 03 - 3

03 Maintenance, Self-diagnosis 944

Tester cable

Diagnosis

Pin 1

Pin 2

Pin 3

Pin 4

Pin 5

Pin 6

Pin 7

Pin 8

Pin 9

Pin 10

Pin 11

Pin 12

plug

unused

Round plug

Pin 4

Pin 1

Pin 7

Pin 6

Pin 2

Pin 5

Pin 3

34

Switch on the ignition

Display:

The ignition must not be switched off

during the entire error diagnosis

procedure.

03 - 4 Connection in the 944 S

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Starting error diagnosis

Condition:

Engine off

Ignition on

Display:

Press the green key until the clear symbol

appears on the function display.

Display:

Clear symbol

The diagnosis sequence for the DME control

unit then takes place.

If an error is displayed - take the note of the

error (e.g. 1211).

Display:

The error is displayed until the green key is

again pressed on the tester. The next

error code is then displayed. if applicable.

This must be repeated until 1000 appears on

the display.

If no error has occurred. the following display

appears.

Display:

Starting error diagnosis

Printed in Germany - XVI, 1987 03 - 5

03 Maintenance, Self-diagnosis 944

Press the green key until the clear symbol ap-

pears on the function display. The following

display must then appear.

Display:

This now terminates diagnosis of the DME

control unit.

If one or several errors (up to 5) has/have

been displayed, the error memory must be

reset; see chapter (Resetting the error

memory).

03 - 6 Starting error diagnosis

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Actuator and input signal function

checking

An actuator and input signal function check

can be carried out independently of an error

diagnosis. This function check tests

individual

components or electrical signals with

respect

to their functioning or signal paths.

Functions

ara triggered from the diagnosis tester.

During

functional checking of components, these

must audibly or tangibly operate and can

thus

be detected as being electrically in proper

working order or defective.

An error display via the tester is not possible

in

this mode, but faulty input signals or their

wiring connection ara detected by the tester.

Starting actuator and input signal

function check

Ignition off

Press the yellow key until the function symbol

(see display) appears on the function display.

Display:

Prass the green key until the clear symbol

ap-

pears on the function display.

Display:

Switch on the ignition within 8 seconds.

Actuator and input signal function checking

Printed in Germany - XVI, 1987 03 - 7

03 Maintenance, Self-diagnosis 944

Press the green key until the ctear symbol

ap-

pears on the function display. This activates

the first testing step and the injection valves

are activated.

Display:

The injection valves must all operate audibly

or tangibly.

Note:

If later attempts are made to start the engine,

starting difficulties may occur because a

slight

residual amount of fuet is injected during this

testing step.

The testing steps remain in operation until the

green key is again pressed on the tester and

the clear symbol appears.

The next testing step is initiated by again

pressing the green key.

Refer to the test code list for the sequence

of

testing steps.

03 - 8 Actuator and input signal function checking

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

As from the "idle contact" testing step,

specific

controls must additionally be operated on the

car for the purpose of function checking.

Idle contact display:

Slightly press the accelerator. The LED must

go off after approx. 20 mm and the display

will

appear After approx. 3 s.

Display:

If this is not the case, an error has occurred

in

the area of the idle contact (see Idle contact

troubleshooting).

If the display 0000 does not appear, it is pos-

sible to switch at all times to the next testing

step. Press the green key until the clear

symbol appears.

Initiate the full load contact testing step.

Display:

Slowly press the accelerator until the full

throttle position is reached.

The LED must go off and the display will

appear after approx. 3 s.

Display:

If this is not the case, an error has occurred

in

the area of the full load contact (see Full load

contact troubleshooting).

Actuator and input signal function checking

Printed in Germany - XVI, 1987 03 - 9

03 Maintenance, Self-diagnosis 944

Initiale the air-conditioning control terminal

41

testing step.

Display:

Switch on the air-conditioning system.

The LED must go off and the display will

appear after approx. 3 s.

Display:

If this is not the case, an error has occurred

in

the area of the air-conditioning system's

wiring.

In the event of an error, check with reference

to the circuit diagram.

Do not switch off the air-

conditioning system.

Initiate the air-conditioning control terminal

40

testing step.

Display:

Switch off the air conditioning system.

The LED must go off and the display will

appear after approx. 3 s.

Display:

If this is not the case, an error has occurred

in

the area of the air-conditioning system's

wiring.

In the even! of an error, check with reference

to the circuit diagram.

03 - 10 Actuator and input signal function checking

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Press the green key until the clear symbol

appears.

Display:

End of the actuator and input signal function

checks.

Actuator and input signal function checking

Printed in Germany - XVI, 1987 03 - 11

03 944

03 - 12 Blank page

944 Maintenance, Self-diagnosis 03

Test code list

Test code Components

1311

1321

1322

1332

1333

1334

1335

Injection valves

Rotary idle controller

Solenoid valve - tank bleeding

Idle contact

Full load contact

Air-conditioning/AC switch

Air-conditioning/compressor coupling

Test code list

Printed in Germany - XVI, 1987 03 - 13

03 944

03 - 14 Blank page

944 Maintenance, Self-diagnosis 03

System adaption

System adaption can be carried out with the

tester. That is to say. the electronic idle control

in the DME control unit is adapted to the

actual air throughput and to the current

condition of the engine.

Note:

For system adaption, it is necessary for the

engine to be at operating temperature.

Ignition off

Press the yellow key the number af times

required for the function symbol to appear

on the function display.

Display:

Press the green key until the clear symbol

appears on the function display. Start the

engine within 8 seconds. Allow the engine to

idle until the system adaption code appears.

Display:

The engine must now idle for at least 30

seconds.

System adaption is then completed.

Ignition off

System adaption

Printed in Germany - XVI, 1987 03 - 15

03 944

03 - 16 Blank Page

944 Maintenance, Self-diagnosis 03

Knock detection

Before knock detection is carried out, error

diagnosis must first of all be performed to

guarantee that no electrical error has

occurred

in the area of the knock control and the

knock

sensors.

Knock detection should not be carried out if

the customer has complained about poor

out-

put or too high a consumption, for instance.

Condition:

The engine most be at operating

temperature

during the test. Testing most be carried out

during a test drive or on the roller test stand.

Knock detection

Engine at operating temperature

While the engine is running, simultaneously

press the yellow and the green key until the

knock detection function symbol appears

on the function display.

Display:

The tester is new in knock detection mode.

Note:

Normal driving is a prerequisite for the

test drive (roller test stand).

Start the test drive (roller test stand).

Press the green key until the clear symbol

appears on the function display.

Display:

Knock detection

Printed in Germany - XVI, 1987 03 - 17

03 Maintenance, Self-diagnosis 944

The tester is now active. If knocking occurs,

this will be indicated by the tester, e.g.:

Display:

After the expiry of 10000 ignitions. the

function

display will change to "r".

Display:

Counting is now complete.

The number af knocks is displayed in per

mill.

In this example. 25 knocks have occurred.

Knock detection must be carried out until the

function display switches over from the clear

symbol to the knock detection symbol. This is

always the case once 10000 ignitions have

occurred. All occurring knocks are added up

and displayed as the end result.

To restart knack detection. the green key

must be pressed until the clear symbol again

appears.

A knock display of > 2.5 (25) draws attention

to an error.

Error possibilities:

Defective cup tappets

Conical rod damage

Crank mechanism damage

To terminale knock detection mode. the

green and yellow keys must be pressed

simultaneously until the display appears.

Display:

03 - 18 Knock detection

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Troubleshooting

Diagnosis using the tester can refer only to

the error path, but not to a defective

component.

Note:

Before troubleshooting, the entire error

memory must be read out.

Error code 1111

The supply voltage is too low

< 10 V or too high > 16 V.

Possible causes for too low a supply

voltage:

Battery exhausted

Poor contact on the grounding strap

Poor contact on the control unit

A defective regulator may be the cause

of

too high a supply voltage.

Troubleshooting

Printed in Germany - XVI, 1987 03 - 19

03 Maintenance, Self-diagnosis 944

Error code 1112

This error code indicates an error in the area

of the idle contact.

Possible error:

Ground fault

Switch stuck

Testing the idle contact

Extract the plug from the DME control unit.

32

Connect a ohmmeter between terminal 52

and terminal 24 on the DME plug.

Display:

Throttle valve closed: R < 10

Throttle valve open: R =

Switchover must already occur if the throttle

valve is only slightly open (approx. 1°).

If the values ara not reached during this

testing

step, measurement must be repeated

directly

on the throttle valve switch.

03 - 20 Troubleshooting

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Error code 1113

This error code draws attention to an error in

the area of the full load contact.

Possible errors:

Ground fault

Switch stuck

Testing the full load contact

Connect an ohmmeter between terminal 53

and terminal 24 on the DME plug.

Display:

Throttle valve closed: R =

Throttle valve in full load position: R < 10

The switching point must be briefly before

full

load.

If the values are not reached in this testing

step, measurement must be repeated

directly

on the throttle valve switch.

Error code 1114

This error code draws attention to an error in

the area of the engine temperature sensor

(NTC 2).

87/912

Possible errors

Ground fault

Short to positive

Wire discontinuity

NTC 2 defective

Testing the engine temperature sensor.

Connect an ohmmeter between terminal 45

and terminal 24 on the DME plug.

Troubleshooting

Printed in Germany - XVI, 1987 03 - 21

03 Maintenance, Self-diagnosis 944

Display

0°C =

15 - 30°C =

80°C =

100°C =

4400 -

1400 -

250 -

160 -

6800

3600

390

21

If the values are not reached in this testing

step, measurement must be carried out

directly on the engine temperature sensor.

The engine temperature sensor (NTC 2) in-

forms the control unit about the current

engine

temperature. It results in mixture enrichment

during cold starts or hot running.

Error code 1121

This error code draws attention to an error in

the area of the air-flow sensor.

87/907

Possible errors:

Ground fault

Short to positive

Wire discontinuity

During this test, the plug af the DME

control unit must be plugged in.

03 - 22 Troubleshooting

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Testing the power supply of the air-flow

sensor:

Ignition on

On the extracted plug of the air-flow sensor, a

voltage of 5 V +- 0,5 V must be measurable

between terminal 3 (positive) and terminal 4

(negative) (if necessary, check by reference

to the circuit diagram).

33

Testing the air-flow sensor

From the extracted plug of the air-flow

sensor,

link plug terminal 3 to air-flow sensor plug ter-

minal 3 and plug terminal 4 to air-flow sensor

plug terminal 4 using an auxiliary cable.

Measure the voltage between terminal 2 of

the air-flow sensor and ground.

Display:

approx. 250 - 260 mV

Detach the top of the air filter.

Using a non-metallic tool, slowly force the

airflow sensor valve to full load position.

A voltage rise must be observed during this

time.

Display:

approx. 0.2 V - ca. 4.6 V

No abrupt voltage changes must be

observed

during opening or closing. (Abrupt voltage

changes. i.e. the air-flow sensor is

defective).

Troubleshooting

Printed in Germany - XVI, 1987 03 - 23

03 Maintenance, Self-diagnosis 944

Error code 1123

When this error code appears, the Lambda

control has detected too rich ar too lean

a mixture.

Possible causes for too lean a mixture:

Lambda probe ground fault

Intiltrated air on the intake side

Intiltrated air on the exhaust side of the

Lambda probe

Injection valve does not open

Ignition cut-out

Fuel pressure too low

Possible causes for too rich a mixture:

No partial vaccum on the pressure

regulator

Injection valve does not close

Return to the fuet tank clogged.

Error code 1124

This error code draws attention to an error

in the area of the Lambda probe.

Possible errors:

Ground fault

Short to positive

Wire discontinuity

Testing the Lambda probe signal.

Figure 87/906

Disconnect the Lambda probe plug.

Note:

The voltage af the Lambda probe must

only

be measured using a digital voltmeter, or

only using a comparable measuring instru-

ment with an internal resistanee (Ri) of no

less than 10 M .

03 - 24 Troubleshooting

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Measure the voltage between pin 1 and

engine

ground.

35

The voltage is within the range of approx. 150

mV - 900 mV depending on the mixture

composition.

Check the cable harness to the DME control

unit with reference to the circuit diagram.

Error code 1125

This error code indicates an error in the

area

of the intake air temperature sensor (NTC

1)

in the air-flow sensor.

Possible errors:

Ground fault

Short to positive

Wire discontinuity

NTC 1 defective

Testing the intake air temperature

sensor.

Connect an ohmmeter between terminal 44

and terminal 26 on the DME plug.

Display:

0°C =

15 - 30°C =

40°C =

4400 -

1400 -

1000 -

6800

3600

1300

If the values are not reached during this

testing step, measurement must be carried

out directly on the intake air tempertaure

sensor.

Connect an ohmmeter between pin 1 and

pin 4 on the air-flow sensor.

Display: as above

Troubleshooting

Printed in Germany - XVI, 1987 03 - 25

03 Maintenance, Self-diagnosis 944

Error code 1131

This error code draws attention to an error in

the area of knock sensor 1.

87/911

Error code 1132

This error code draws attention to an error in

the area of knock sensor 2.

87/910

Error testing of the knock sensors is an

active

error test, i.e. error testing is carried out

during

driving.

If an error has occurred, first check the

wiring

for a ground fault, a short to positive and for

continuity with reference to the circuit

diagram

before replacing the knock sensor.

03 - 26 Troubleshooting

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Error code 1133

Error code 1133 draws attention to an

error in

the area of the knock control in the DME

con-

trol unit. If this error code appears, the

DME

control unit must be replaced.

Error code 1134

This error code draws attention to an error in

the area of the Hall generator.

87/904

Possible errors:

Ground fault

Short to positive

Wire discontinuity

Testing the Hall generator signal

Using a suitable auxiliary æble, connect an os-

cilloscope to the diagnosis plug, pin 9 (square-

wave signal) and pin 2 (ground). If the Hall

gen-

erator signal is O.K., the following picture must

appear on the oscilloscope's screen.

Troubleshooting

Printed in Germany - XVI, 1987 03 - 27

03 Maintenance, Self-diagnosis 944

Testing the Hall generator's power supply

Disconnect the Hall generator's connector.

Ignition on

36

A voltage of 12 Volt +- 1 V must be

measurable between pin 1 (positive) and pin

3

(negative). If this is not the case, check the

wiring with reference to the circuit diagram.

Error code 1141

Error code 1141 draws attention to an error

in

the area of the DME control unit. If this error

code appears, the DME control unit must be

replaced.

03 - 28 Troubleshooting

Printed in Germany - XVI, 1987

944 Maintenance, Self-diagnosis 03

Error code - List

Error code

1500

1000

1111

1112

1113

1114

1121

1123

1124

1125

1131

1132

1133

1134

1141

Error path

No error

Output end

Supply voltage too low/high

Idle contact

Full load contact

NTC 2

Air-flow sensor

Lambda control detects a too rich / too lean mixture

Lambda probe signal not correct

NTC 1

Knock sensor 1

Knock sensor 2

Knock control in the control unit

Hall generator signal

DME control unit

A digit 2 (e.g. 1211) may appear in the second error code digit position to indicate "sporadic

errors", i.e. an occasionally occurring error.

This does not apply to error codes 1000 and 1500.

Error code - List

Printed in Germany - XVI, 1987 03 - 29

03 944

03 - 30 Blank page

944 Maintenance, Self-diagnosis 03

Resetting the error memory

Once the DME control unit error diagnosis

has been completed. this is completed by

error code 1000. The error memory cannot

be reset as follows until this error code

appears:

The yellow key must be pressed until the

function symbol (see display) appears on

the function display.

Display:

Function symbol

The green key must be pressed until the

clear

symbol appears on the function display.

Display:

The error memory is reset if the LED goes

off

and the function display changes to 0000.

Display:

Note:

A test drive must be carried out after

resetting

the error memory.

At the same time, pay attention to the

following:

1.

The engine must be at operating

tempera-

ture. i.e. at least 80°C.

2. The duration ot the test drive (minimum 6

minutes).

3. At the end ot the test drive. run the

engine

for at least 60 seconds without opening

the

throttle valve.

After the test drive, read out the error

memory

once again.

Resetting the error memory

Printed in Germany - XVI, 1987 03 - 31

03 Self-diagnosis 944

Operating conditions for start of diagnosis

Systems Ignition on

Engine standing still

Engine running

944 S / 944 S2

DME

Airbag

Alarm system

yes

to n < 2000 rpm

yes

Webdesign from www.9ss1.dk/porsche944

03 - 32 Operating conditions for start of diagnosis

Printed in Germany - XXIV, 1991

944 Self-diagnosis 03

Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991 03 - 33

03 Self-diagnosis 944

1. General information

1.1 Application

The Systemtester 9288 (BOSCH KTS 301) is a microprocessor-con-

trolled self-diagnosis tester.

All systems which have a diagnosis interface as per ISO Standard can

be tested with this tester. The following tests are possible:

* Reading out the fault memory

* Testing of the actuators

* Testing the circuit inputs

* System adaptation

* Engine-knock detection

* Sensor and status checks, tire-pressure monitoring (RDK)

The Systemtester 9288 is a high-quality pjece of electronic equip-

ment In order to prevent damage to the equipment as a result of

improper use, please read the information in the operating

instructions carefully and comply with it.

In addition. the instructions (specifications) of the vehicle manufac

turer are also to be observed.

If the tester should fail, check the following points before sending it

in for repair:

1. Has the tester been operated incorrectly?

2. Is the battery sufficiently charged?

3. Is the adapter cable OK?

(Please note when checking the adapter cable that a highly sensi-

tive electronic matching circuit is installed in the vicinity of the 19-

pore plug).

1.2 Construction (Fig. 1)

No.

Description Function Remarks

1 LCD indicator Dot matrix 5 x 8

4 lines each with 20 characters

Foreign languages possible

Illumination

If the Systemtester 9288 is switched on

without the program module, following

the self-test the tester switches off auto-

matically and informs the user that the

program module is not fitted.

2 Keyboard Keys 1, 2, 3

=

Selection key

Keys < > =

Previous peget next page

Key H =

Help menu, e.g.:

Illumination

Screens stored

Control-unit overview

Setting up printer

Switching off unit

Key N =

Return to the next higher

program level following

termination of a test

sequence or, during a test

sequence, return to the

last display

Key =

Storing indication

Key =

Playing back

stored reading

Switching on

=

Press any key

Switching off

(automatic) =

180 s after last

depression of a key or

if no data stream flows

across the seriel

interface.

The last fjeld in the top right-hand corner is

filled completely, this means that this is a

stored figure and not an actual,

real-life figure.

Fitted accumulator with NiCd batteries.

The Systemtester 9288 must be switched off

during the initial battery charging process.

Charging time > 8 hours

Discharged upon delivery. Following charge:

Operating time:

4 - 8 hours without scale illumination

1 - 2 hours with scale illumination

Connection to vehicle battery by means

of vehicle-specific adapter lead (see 1.4) Connection through ISO-interface

Charging voltage supply

3 Power supply

If the voltage is not sufficient,

"Charge battery" appears

on the display. If this is

not done, the unit switches

itself off. Battery charger (accessory) For test operation and for charging

the NiCd batteries.

4 Connection for

Input and output devices Connection facility for Printer

e. g. Epson, IBM. Hewlett Packard (HP) The Systemtester 92BB transmits data with

the following configurations:

8 data bits / 1 start bit / 1 stop bit /

No parity (for printer matching)

5 Connection for vehicle

specific adapter lead Reading out the data Input for flashing-code support

6 Plus-in programme module

(see also Figure 2)

C-MOS !

Do not touch plug !

Operating system

LCD drive

Keyboard

Interface communication

Computations and data conversions

Plug in module:

remove rubber protector,

insert modul e fully.

03 - 34 Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991

944 Self-diagnosis 03

1.3 Battery charger run off mains voltage (Figure 3)

- Accessory -

Item 1 Charger with connecting cable, 1.5 m long

Item 2 8-pin AMP plug

1.4 Vehicle-specific adapter cable

Porsche No. 000 721 928.81

1.5 Connecting lead (Figure 4)

- Self-fabrication -

for printer, programme load station or similar unit.

For interface-trunk assignment, see manual of corresponding unit.

Printer cable for standard D 25

BOSCH No. 1 684 465 193

Printer cable for EPSON

BOSCH No. 1 684 465 194

2. Connection

The following points must be observed:

- No gear must be engaged on the vehicle (Automatic transmission

in position N - P) - Danger of Accident!

- ALL work on the vehicle must only be carried outwith the ignition

switched off.

After having connected the vehicle-specific adapter cable, the in-

structions listed under "3" ara displayed on the Systemtester 9288:

2.1 Charging with the battery charger (Fig. 3)

Connecting the Systemtester 9288 to the battery charger.

(Fig.1, pos.5).

2.2 Diagnosis

Connecting the Systemtester 9288 to the diagnosis plug in the

vehicle by means of the vehicle-specific adapter cable.

Switch on the tester and proceed according to the instruetions

displayed.

3. Testing

Scope of module:

Guidance through the menu, communication with the ECU, reading

out the error memory and selection of the "Help" menus, actuator

diagnosis, circuit inputs and system adaptation, engine-knock detec-

tion, sensor and event check for the tire-pressure monitor (RDK).

3.1

Reading-out the error memory

Connect the Systemtester 9288 (see 2.)

Switch on the Systemtester,

(possible with every key!)

Display:

PORSCHE

Eprom modul

Mod. intro.

xx.xx.xx

eng

If a specific instruction does not appear in a display, it is always

possible to proceed by pressing the button >.

Due to the fact that the Systemtester 9288 can store error displays

(see Chapter 3.7), the following display will appear if errors have

been stored in the image memory:

Stored displays

erased ?

1 = yes

3 = no

Key 3

Display:

Print out

displays:

continue:

H

>

H = Help menu (see 3.6) or key 1

Display:

Vehicle types

1 = 944 S

2 = 911 Carrera 4

3 = 928 S 4

Selection of the vehicle type with key 1, 2 or 3.

After the vehicle type has been selected, the following

instruction appears:

Connect adapter

cable to veh. plug.

Ignition "ON".

After completion:

>

The following then appears:

Wait for

Data

Break off test:

N

After a short pause. the Systemtester 9288 reperts all the sys-

tems that are installed in the particular vehicle. If a system is pre-

ceded by " # ", this means that at least 1 error is stored in that

particular system.

Examples:

Installed systems

1 = # LH

2 = # EZK

3 = RDK

The particular system can be selected by means ef key 1, 2 or 3.

After selection (for instance with key 1), the following display

appears:

LH

System:

Ser. No.:

RB. No.:

L01 LH-JET

92861812313

0280002507

Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991 03 - 35

03 Self-diagnosis 944

After pressing the key > , a selection menu is displayed:

Menu

1 = Fault memory

2 = Drive links

3 = Input signals

>

< Menu

1 = System adaptation

In the example - press key 1. There then follows the display of

the number of errors which are stored (if any).

Number of

faults

- 2 -

Proceed with key >

Additional info to

every display with

key 1

continue:

>

Proceed with key >

Error output:

1: Engine

temperature sensor 2

Short to ground

not present

If key 1 is pressed instead of the > key, the corresponding error

code display appears (the last two digits of the flashing code).

Fault code: - 14 -

Proceed with key >

Further errors are displayed (if they exist):

2 : Idle contact

Short to ground

present

If key 1 is pressed instead of key > the corresponding error-code

display appears (the last two digits of the flashing code).

Fault code: - 12 -

After the last displayed error, the following instruction appears:

Repair fault accord-

ing to repair

instructions

Continue:

>

Proceed with key >

Fault repaired ?

1 = yes

3 = no

Return to display "No. of errors" with key 3.

Proceed with key 1:

Fault memory

1 = Erase

3 = Do not erase

If key 3 is pressed:

= Return to menu "error memory".

The error memory is not erased!

Proceed with key 1:

Fault memory

has been cleared

Return:

N

The test scope "Read-out error memory" is terminated

at this point.

3.2 Actuator diagnosis

If an actuator is selecled, this is triggered by the ECU so that it can

be checked for correct functioning.

The various actuators components are gone through one after

the other and are selected with the > key.

Operate the Systemtester 9288 as described under 3.1 until

the following menu display appears:

Menu

1 = Fault memory

2 = Drive links

3 = Input signals

>

After pressing key 2, the display for the first actuator appears:

Injector

to activate

1 = Start

Continue:

>

If key > is pressed, the next actuator is selected.

Pressing key 1 results in the following instruction:

Can injectors be

heard / felt?

1 = yes

3 = no

03 - 36 Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991

944 Self-diagnosis 03

Key 1 selects the next actuator (e. g. idle actuator). Following

instruction:

Repair fault accord-

ing to repair

instructions

Continue:

>

After pressing key > , the following display appears:

Injector

to activate

1 = Start

Continue:

>

Proceed with key 1

Can injectors be

heard / felt?

1 = yes

3 = no

Proceed with key 1 to the next actuator.

Idle stabilizer

to activate

1 = Start

Continue:

>

Proceed with key 1

Can idle stabilizer

be heard / felt?

1 = yes

3 = no

By pressing key 1, the next actuator is selected. After pressing

key 3, the next instruction appears:

Repair fault accord-

ing to repair

instructions

Continue:

>

Proceed with key >

Idle stabilizer

to activate

1 = Start

Continue:

>

After pressing key 1. the following display appears:

Can idle stabilizer

be heard / felt?

1 = yes

3 = no

By pressing key 1. the next actuator is selected. The actuators are

selected one after the other and triggered until the following

display appears:

Drive link test

completed

Return:

N

By pressing the key N. the operator is returned to the menu.

3.3 Circuit inputs

In addition lo the actuators, the Systemtester 9288 can also

check circuit inputs. To this end, operate the Systemtester 9288

in accordance with 3.1 until this menu display appears:

Menu

1 = Fault memory

2 = Drive links

3 = Input signals

>

Press key 3

Idle contact

1 = Start

Continue:

>

By pressing key > the next circuit input is selected.

The next display appears when key 1 is pressed.

Activate accl. pedal

Idle contact

- closed -

Continue:

>

Operate the accelerator pedal, the following display appears:

Activate accl. pedal

Idle contact

- open -

Continue:

>

The next circuit input is selected by pressing key >. Repeat until

this display appears:

Input signals

testing compleled

Return:

N

Press key N for return to menu

3.4 System adaptation

When the function "System adaplation" is triggered. the ECU re-

gisters the basic air requirement of the engine.

To this end. operate the Systemtester 9288 as per 3.1 until the

following menu display appears:

Menu

1 = Fault memory

2 = Drive links

3 = Input signals

>

Proceed with key >

< Menu

1 = System adaptation

Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991 03 - 37

03 Self-diagnosis 944

Proceed with key 1

Prerequisite:

Eng. at oper. temp.

with all consumers

and ignition off.

Proceed with key >

System adaptation

1 = Start

Return:

N

If key N is pressed

= return to menu.

If key 1 is pressed:

Start engine !

Following engine start there appears:

System is being

adapted

Please wait !

Atter approx. 30 secs there appears:

System adaptation

completed

Return:

N

If it is impossible to carry out system adaptation (idle contact not

closed, or delective). the following display appears:

No system adapta-

tion possible

Idle contact ?

Return:

N

Atter cornpletion of the system adaptation, return to the menu

with key N.

3.5 Engine-knock registration

The engine-knock registration function can only be triggered

through the EZK or DME control unit.

To this end, operate the Systemtester 9288 as described in 3.1

until the following display appears:

Installed systems

1 = # LH

2 = # EZK

3 = RDK

The particular system can be selected by means of key 1, 2 or 3.

For instance with key 2 the folIowing display appears:

EZK

System: E01EZK

Ser. No.: 92861812415

RB. No.: 0227400154

Proceed with key >

The following menu display appears:

< Menu

1 = Fault memory

2 = Knock registration

Proceed with key 2

Condition:

Engine at operating

temperature

>

Proceed with key >

< Start knock

registration before

test drive

>

Proceed with key >

< A normal test

drive is a pre-

requisite

>

Proceed with key >

< Stop the test

drive only if the

display with the no.

of knocks comes on.

Proeeed with key >

Knock registration

1 = Start

Return:

N

Pressing key 1 activates the engine-knock counter:

Knoek registration

in progress

Please wait !

03 - 38 Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991

944 Self-diagnosis 03

The knock counter registers 10,000 ignitions before the display

with the actual number of combustion "knocks" appears.

Number

Knocks:

Combustion:

Continue:

xxx

xxxxx

>

Proceed with key >

Knock registration

completed

Return:

N

If knock registration is impossible (due to lack of engine-speed

signal), the following display appears:

No knock regist-

ration possible.

RPM signal?

Return:

N

Following completion of the knock registration test, return to the

menu with key N.

3.6 Help menu

The "Help" menu can be selected from every display by pressing

key H. Return to the initial display with key N.

Help menu

1 = Illumination

2 = Display stored

3 = Ctrl. unit chart

>

Proceed, for instance with key 1:

Key 1:

The scale illumination is switched on and the tester returns to the

previous display.

Or with key 2:

Data display stored

1 = Print

2 = Clear

Proceed with key 1

Stored displays ara printed out (If printer connected).

Proceed with key 2

Stored displays are erased.

With the "Help" menu, for instance

Help menu

1 = Illumination

2 = Display stored

3 = Crtl. unit chart

>

If the key > is pressed, a further section of the "Help" menu is

displayed:

< Help menu

1 = Printer setting

2 = Switch of! equip.

3 = Baud Rate

Proceed for instance with key 1

Printer setting

1 = IBM

2 = HP Quiet Jet

3 = EPSON

The selection of the printer results in the tester being set up for

the printer type in question.

3.7 Store measurement displays (Key )

Using key , all displays can be stored manually.

The following displays are stored automatically:

- ECU-Identity

- Installed systems

- All existing errors

When the memory limit is reached, the following instruction

is displayed:

Data display mem.

full !

Return:

N

3.8 Show stored measurement displays (Key )

Using the keys < or >, the stored displays for the selected

system can be shown.

The stored displays can be called up by means of the key.

The system selection (LH - EZK - RDK) takes place with the keys

1, 2 or 3.

4. Service and wear parts (BOSCH)

Fig. BOSCH Part No. Designation Comment

1/3

4/1

4/2

4/3

1 687 335 002

1 684 483 152

1 684 485 170

1 680 552 005

1 684 465 193

1 684 465 194

NC- battery

Plug

Socket

Screwed cap

Printer cable

(Standard D25)

Printer cable

(EPSON)

9 pole

4.1 Service parts (Porsche)

Designation Porsche Part No. Special tool No.

Systemtester 9288

Adapter cable

Battery charger

Module (D)

Module (GB/USA)

Module (F)

Module (I)

Module (E)

000.721.928.80

000.721.928.81

000.721.928.82

000.721.928.84

000.721.928.85

000.721.928.86

000.721.928.87

000.721.928.88

9288

9288/1

9288/2

9288/4

9288/5

9288/6

9288/7

9288/8

Operating instructions for System Tester 9288

Printed in Germany - XXIV, 1991 03 - 39

10 944

10 - 0100 Blank page

944 Engine, Crankcase 10

Tightening torques for engine (16-valve)

Location Thread Tightening torque Nm (ftlb)

Crankshaft/

crankcase

Upper and lower

crankcase sections

(studs)

Knock sensor

Cylinder head

Cylinder head to upper

crankcase section

Engine type M 44.40

Engine type M 44.41

(3.0 l)

Camshaft bearing to

cylinder head

Allen screws for chain

tensioner

Banjo bolt /

Chain tensioner

Cover for cylinder head

Fastening /

Hall sensor

M 12 x 1.5

M 10

M 8

M 6

M 8

M 12

M 8

M 6

M 8 x 1

M 6

30(22)

60 ° torque angle

20(15)

50(37)

1 st stage

2nd stage

1 st stage

2nd stage

20(15)

10(7.5)

20(15) original screw

without washer

refer to Page 15 - 110

20(15)

90 ° torque angle

20(15)

60 ° torque angle

90 ° torque angle

1 st stage

2nd stage

3nd stage

1 st stage

2nd stage

3nd stage

20(15)

10(7.5)

Tightening torques for engine (16-valve)

Printed in Germany - XIX, 1989 01 - 0101

10 Engine, Crankcase 944

Tolerances and wear limits

Engine M 44.40/41

Cooling system

Coolant thermostat

Cooling system cap

Pressure valve

Vacuum valve

Oil circuit

Oil consumption

Oil pressure

at 80° C oil temperature:

at 5,000 rpm

Oil capacity

Difference of quantity between

dipstick marks

Valve timing

Camshaft bore

Camshaft

Bucket tappet bore

Bucket tappets

Camshaft

Opening temperature

opens at excess pressure

opens at vacuum

l/600 miles

excess pressure

6 l, from MY '88

Inner dia.

Dia.

Axial clearance

Inner dia.

dia.

Runout

For installing

(new) Wear

limit

81-85° C

1.3...1.5

0.1 bar

approx. 1.5

approx. 4 bar

6.5 l

approx. 1.5 l

28 + 0.021

- 0

28 - 0.04

- 0.055

0.08...0.18

35 - 0.025

- 0.041

35 - 0.025

- 0.041

0.02

10 - 0102 Tolerances and wear limits

Printed in Germany - XXIV, 1991

944 Engine, Crankcase 10

Tolerances and wear limits

Engine M 44.40/41

Cylinder head with valves

Mating surface

Valve seat width

Exhaust

Seating angle

Outer correction angle

Inner correction angle

Valve guides:

Valve stem:

Intake

Exhaust

Valve guide/valve stem

Intake

Exhaust

Compression

Pistons with connecting rods

Cylinders/pistons

Piston rings M 44/40

Piston rings M 44/41

Piston rings M 44/40

Piston rings M 44/41

Distortion

Intake:

Inner dia.

Dia.

Rocking clearance

Clearance

Height clearance

Groove 1

Groove 2

Groove 3

Groove 1

Groove 2

Groove 3

Ring gap clearance

Groove 1

Groove 2

Groove 3

Groove 1

Groove 2

Groove 3

For installing

(new)

1.5

1.8

45°

30°

60°

7 + 0.015

6.97 - 0.012

6.94 - 0.012

8 bar and

above

0.008-0.032

0.040...0.075

0.020...0.055

0.040...0.075

0.030...0.065

0.020...0.055

0.20...0.40

0.20...0.45

0.30...0.60

0.20...0.50

0.20...0.55

0.30...0.90

Wear

limit

max. 0.05

0.8

6.5 bar

approx.

0.080

Tolerances and wear limits

Printed in Germany - XXIV, 1991 10 - 0103

10 Engine, Crankcase 944

Tolerances and wear limits

Engine M 44.40/41

Con rod bush

Piston pin

Con rod bush/piston pin

Crankshaft and cylinder block

Crankshaft

measure at bearing 2, 3 or 4

Bearing 1 and 5 on prisms

Con rod journal

Con rod/crankshaft

Crankshaft beanng journal

Crankshafts/

crankshaft

Crankshaft bearing/

crankshaft

Cylinder bore

Bore for balance shaft bearing

sheIIs at crankcase or

balance shaft cover

Bore for bushing in

bearing housing

Balance shaft

Dia.

Radial clearance

Runout

Dia.

Radial clearance

Axial clearance

Dia.

Radial clearance

Axial clearance

Out-of-round

Dia.

For installing

(new)

24 + 0.018

+ 0.028

24-0.004

0.018-0.032

0.046

51.971-51.990

0.027-0.069

0.080...0.240

69.971-69.990

0.028-0.070

0.060...0.192

0.010

34.000...34.019

30.975...30.991

Wear

limit

max. 0.06

0.16

0,40

0,020

10 - 0104 Tolerances and wear limits

Printed in Germany - XXIV, 1991

944 Engine/Crankcase

10

REMOVING AND INSTALlING ENGINE (16-VALVE ENGINES)

TOOLS

No. Description Special Tool Remarks

Engine suspension

beam

3033

(VW Special Tool)

In conjunction

with workshop

crane, e.g

Bilstein K750 H.

Note:

If necessary, use a commercially available carabiner (load-bearing capacity

650 kg) to connect engine suspension beam to workshop crane.

Printed in Germany - XIII, 1987 Removing and Installing Engine 10 - 101

10 Engine/Crankcase 944

REMOVING AND INSTALLING ENGINE (MANUAL TRANSMISSION)

Remove by lowering engine from car.

The bell housing remains attached

to the engine.

Removing

1.

Align lifting platform pads

beneath jacking points and raise

car.

2.

Place protective covers on

fenders.

3.

Unbolt and remove front wheels.

4.

Disconnect battery/bodywork

ground lead. Disconnect battery

positive lead. Disconnect wire

harness and push both cables with

rubber grommets through splash

wall. Open cable clips.

5.

Unbolt panel in passenger-side

footwell and remove. Unbolt

carrier plate for DME control

unit and disconnect control-unit

plug. Disconnect 8-pin connector.

6.

Slacken hose clamp for fuel

return line and disconnect hose.

Disconnect fuel feed while

countering. Detach cable from

tempostat serve motor. Disconnect

series resistor/injection nozzle

connector.

10 - 102 Removing and Installing Engine Printed in Germany

944 Engine/Crankcase

10

7.

Disconnect breather hose for

toothed helt cover at rear of

lower section of air filter.

Unbolt filter assembly as a unit

and remove.

8.

Remove air-flow sensor.

9.

Slacken and remove

ignition-distributor cap and

rotor. (Mark installation

position of rotor). Remove oil

filter and ATF reservoir.

10.

Remove throttle valve actuating

cable complete with reversing

roller and holder. Disconnect

oxygen sensor plug connector.

Slacken hose clamps at intake

manifold and brake booster and

disconnect hoses.

11.

Remove cable clips from

bulkhead. Disconnect two-pin and

multi-pin connectors. Disconnect

vacuum hose from tank breather

valve.

Printed in Germany - XIII, 1987 Removing and Installing Engine 10 - 103

10 Engine/Crankcase 944

12. Remove engine underguard.

13.

Open coolant drain plug and

catch coolant in a suitable

container. Disconnect alternator

breather hose.

14.

Disconnect coolant hose at

bottom right of radiator from

engine and remove. Catch any

coolant which may be left.

15.

Disconnect electric leads from

fan motors, detach fan-motor

bracket from radiator and remove

by lowering from car.

16.

Slacken coolant hose and

breather hose from top left of

radiator and remove. Disconnect

electrical connection from

temperature switch to radiator.

Disconnect coolant hose from

expansion tank and remove.

17.

Disconnect radiator at brackets

and remove radiator by lowering

from car.

18.

Attach support beam 10-222 A to

front transport bracket of

engine and hold engine in

installation position. Check

that beam is correctly attached.

10 - 104 Removing and Installing Engine Printed in Germany

944 Engine/Crankcase

10

19.

Detach Poly-rib belt tensioner

from air-conditioning compressor

and remove belt. Remove

compresor from bracket and place

to one side. (Do not disconnect

refrigerant hoses).

20.

Unbolt stabilizer with bracket

from body and from control arms

and remove. Disengage left and

right tie rods.

21.

Slacken hose clamps between ATF

cooler and steering and

disconnect line.

22.

Disconnect servo pump from

bracket, moving spacer sleeve

forward to remove. Leave servo

pump hanging from steering.

23.

Disconnect left and right

control arms from front-axle

traverse and rear bearings and

pull forward to remove. (Do not

slacken bolts in bearing bracket).

24.

Unbolt universal joint from

steering detach hydraulic motor

mount from engine supports and

lower front-axle cross member

complete with steering and servo

pump from car.

Printed in Germany - XIII, 1987 Removing and Installing Engine 10 - 105

10 Engine/Crankcase 944

25.

Disconnect leads from starting

motor and remove starting motor.

26.

Remove clutch actuating cylinder

from bell housing. (Leave line

connected). Unbolt and remove

holder for line from upper

crankcase half.

27.

Disconnect exhaust from flange of

exhaust manifold and disconnect

exhaust extraction line. Remove

oxygen-sensor cable from bodywork.

28.

Disconnect flange downstream of

catalytic converter and suspension and

remove system.

29.

Remove upper transaxle/bell

housing mounting bolts.

30.

Disconnect coolant hoses for

heating above exhaust manifold

and from cylinder head.

31.

Attach VW Special Tool 3033

suspension beam to transport

bracket of engine as follows:

Pulley end:

Flywheel end:

Position 2

Position 12

In position 2, the threaded rod is

beneath" the suspension beam. In

position 12, the threaded rod is

"above" the beam.

32.

Tighten workshop crane e.g.

Bilstein K750 H slightly to take

part af engine weight and remove

support beam 10 - 222A.

Note:

Threaded rod af support beam

10 - 222A remains in front

suspension eye.

33.

Remove lower transaxle/bell

housing mounting bolts.

10 - 106 Removing and Installing Engine Printed in Germany

944 Engine/Crankcase

10

34.

Pull engine forward, push rubber

sleeve out of firewall toward

engine compartment and

carefully

pull wire harness out of

passenger-side footwell.

35.

Separate engine from central

tube/central shaft and lower

from car.

Installing

Note the following:

1.

Carefully feed wire harness for

DME control unit, 8-pin connector

and multi-pin connector into

passenger-side footwell.

2.

Begin by screwing transaxle/bell

housing mounting bolts into

place, but do not tighten.

Note:

Do not tighten mounting bolts fully

until hydraulic motor bearing has

been attached to the front-axle

cross member. Tightening torque of

mounting bolts: 42 Nm (31 ftlb).

3.

Install control arms, pressing

sleeve in rubber-metal bearing

down slightly to facilitate

installation.

4.

Place a 4mm thick steel washer in

each of the threaded connections

between the right-hand engine

support (viewed in the forward

direction of travel) and the

hydraulic motor bearing.

5.

Check that the radiator is

correctly seated on the rubber

mounts.

6.

Tighten nuts and bolts to the

specified torques.

Tightening torques:

Stablizer to

aluminium control arm

25 Nm (18 ftlb)

Track rod to

steering knuckle

(locknut)

50 Nm (37 ftlb)

Steering -

universal joint 30 + 5 Nm (22 +

3.6 ftlb)

Control arm to

cross member 65 Nm (48 ftlb)

Cross member

to body 85 Nm (53 ftlb)

Printed in Germany - XIII, 1987 Removing and Installing Engine 10 - 107

10 Engine/Crankcase 944

7.

Refill system with coolant and

bleed system.

8.

Fill reservoir with ATF and bleed

steering system.

9. Run engine until it reaches

operating temperature, check

engine-oil level and coolant

level, top up if necessary.

10 - 108 Removing and Installing Engine Printed in Germany

944 Engine/Crankshaft, Pistons

13

PISTONS. '87 MODELS ONWARD

(16-VALVE ENGINES)

Engine M 44.40 worldwide

Compression: 10.9 : 1

Nominal dia. 100.00 mm

An arrow pointing toward the belt

pulley indicates the installation

position.

1 -

2 -

3 -

Plain compression ring.

chrome-plated

Oil scraper ring

Three-

part oil wiper ring

Printed in Germany - XIII, 1987 Notes on Assembly, Pistons,

'87 Models Onward 13 - 101

13 Engine/Crankcase, Pistons 944

Checking pistons and cylinder bores

Motortype M 44.40

Repair Stage Piston Ø

(mm)

Fa. Kolbenschmidt

Cylinder bore dia.

(mm) tolerance group

code

Standard size 99.980

99.990 +- 0.007

100.000

100.010 +- 0.005

100.020

0

1

2

Oversize 1 100.480

100.490 +-0,007

100.500

100.510 +- 0.005

100.520

I 0

I 1

I 2

Checking pistons

Measure approx. 61 mm from piston crown,

90° offset from piston pin axis.

Checking cylinder bores

Measure approx. 61 mm from upper edge of

cylinder bore, transverse to engine block.

Mount lower crankcase section and tighten

bolts to specified torque for measuring.

Note

It recommended that the stocks of the relevant tolerance group are checked befare machining

the cylinders. If necessary, hone to the piston size available.

In some cases, certain tolerance groups may be in short supply.

13 - 102 Checking pistons and cylinder bores

Printed in Germany - XXV, 1992

944 Engine/Crankshaft, Pistons 13

Pistons from Model 89 onwards

Engine M 44. 41 (3.0 I) worldwide

Compression ratio: 10.9 : 1

Nominal Ø 104.00 mm

The installation position is indicated by the

enlarged intake-valve pockets.

171/13

Checking pistons and cylinder bore

Engine type M 44.41 (3.0 l)

Repair size Piston Ø

(mm)

MAHLE

Cylinder bore

(mm) Tolerance groups

Code

Standard 103.980

103.990 +- 0.007

104.000

104.010 +- 0.005

104.020

0

1

2

Oversize 1 104.480

104.490 +- 0.007

104.500

1 04.500

104.510 +- 0.005

104.520

I 0

I 1

I 2

Checking pistons

Measure approx. 52 mm from crown of pis-

ton, 90' offset to axis of piston bolt.

Checking cylinder bore

Measure approx. 52 mm from top edge of

cylinder bore, across cylinder block.

For measurement, mount lower crankcase

section and tighten with prescribed tightening

torque.

Note

It is recommended that the stocks of the relevant tolerance group are checked before

machining

the cylinders. If necessary, hone to the piston size available.

In some cases, certain tolerance groups may be in short supply.

Pistons from Model 89 onwards

Printed in Germany - XXV, 1992 13 - 103

13 944

This page are missing or blank in the book !

13 - 104 Blank

944 Engine/Crankshaft, Pistons 13

Assemble cover of centrifugal oil

compartment in upper crankcase

section.

Notes on installation

Model 89 onward,

Engine type M 44.41 (3.0 l)

Note

Under normal conditions. it is not necessary

to remove the cover when overhauling an

engine. If the cover is removed, however, the

bolt area must be heated with a hot-air blower

under all circumstances. Apply Loctite 270 to

hexagon head screws.

Observe coding on the cover.

88/342

Assemble cover of centrifugal oil compartment

Printed in Germany - XIX, 1989 13 - 105

15 944

15 - 100 Blank page

944 Engine/Cylinder

15

This page are missing or blank in the book !

Printed in Germany Unknow page

15 - 101

15 Engine/Cylinder 944

This page are missing or blank in the book !

15 - 102 Unknow page Printed in Germany

944 Engine/Cylinder Head, Valves

15

Adjusting with dial gages

2.

Align dial gage with improvised

extension (205 mm long) on piston

crown {cylinder 1). 3 mm

pretension.

Align second gage with hydraulic

tappet of cylinder 1 intake

valve. The dial gage must be

aligned perpendicular to the

intake valve. 3 mm pretension.

3.

Remove distributor rotor and lock

camshaft sprocket with 3

M 5 x 15, to prevent camshaft

sprocket or camshaft turning when

camshaft central bolt is

slackened.

4.

Slacken camshaft central bolt -

note that it is essential to

counter. Slacken temporary

retaining bolts. Turn engine in

direction opposite to direction

of rotation until camshaft

sprocket reaches stop inside

feather-key groove

5.

Tighten temporary retaining bolts

(6 Nm, 4.4 ftlb) and central bolt

(approx. 40 Nm, 30 ftlb).

Printed in Germany - XIII, 1987 Checking an Adjusting

Camshaft Settings

15 - 103

15 Engine/Cylinder Head, Valves 944

6.

Turn the engine in the direction

of rotation until piston reaches

its upper limit af travel.

7. Set dial gage af cylinder 1

intake-valve hydraulic tappet to 0.

8. Turn crankshaft past ignition TDC

(cylinder 1) while observing

cylinder 1 intake-valve dial

gage. Turn engine until gage

shows 1.4 +- 0.1 mm lift.

Note:

Do not turn engine in direction

opposite to direction of rotation.

9. Slacken central bolt and

temporary retaining bolts; while

doing so, ensure that the reading

of 1.4 + 0.1 mm an the dial gage

is not changed.

10.

Now turn crankshaft slowly until

dial gage shows that piston

has reached the upper limit of

travel. With the crankshaft in

this position, the camshafts are

at ignition TDC for

cylinder 4.

11.

Tighten temporary retaining

bolts and central bolt.

Tightening torque of central

bolt: 65 - 70 Nm (48 - 52 ftlb).

12.

Recheck by turning crankshaft

through another 2 turns and

checking setting.

13.

Remove temporary retaining bolts

and install distributor rotor.

15 - 104 Checking an Adjusting

Camshaft Settings Printed in Germany

944 Engine/Cylinder Head and Valve Drive 15

Checking or adjusting camshaft setting for Model 89 onward

Engine type M 44.41 (3.0 l)

Note

The timing has changed with installation of

new camshafts for engine type M 44.41 (3.0 l)

for Model 89 onward.

Setting

Inlet valve cylinder 1

Testing and adjusting value 0.75 +- 0.1 mm

The camshaft is adjusted according to the

same procedure as described on Page

15 - 102.

Checking or adjusting camshaft setting f. Model 89 onward

Printed in Germany - XIX, 1989 15 - 104a

15 Engine/Cylinder Head, Valve Drive 944

Applying the TDC mark on the camshaft sprocket

Engine type M 44.40 / 41 (3.0 l)

Note

Camshaft sprockets available from the spare

parts department do not have a TDC mark.

This TDC mark is applied after the camshaft

timing has been set on the new engine.

1.

Position the new camshaft sprocket over the

old sprocket and transfer the TDC mark to

the new sprocket using a color pencil.

2. Fit new camshaft sprocket and adjust

camshaft timing as described in the Repair

Manual, page 15-102 to 104.

3. After operation 12, page 15-104, has been

carried out, engrave the TDC mark in its

final position on the new camshaft sprocket

using a three-square-file as described on

page 15-102, Fig. 1.

15 - 104b Applying the TDC mark on the camshaft sprocket

Printed in Germany - XXIV, 1991

944 Engine/Cylinder Head, Valves

15

TOOLS - REMOVING AND INSTALLING CAMSHAFTS AND CYLINDER HEAD,

DEGREES-OF-TURN METHOD OF TORQUING (16-VALVE ENGINES)

No. Description Special Tool Remarks

1

2

3

4

Assembly bridges for

installing camshafts

Pressure piece for

sealing ring

Assembly drift for

sealing ring

Angle reader

9248

9234

9233

In conjunction with

clamping bolt from

Special Tool 9226

Commercially available

e.g. Stahlwille No. 715/20

Printed in Germany - XIII, 1987 Tools - Removing and Installing

Camshafts and Cylinder Head 15 - 105

15 Engine/Cylinder Head, Valves 944

REMOVING AND INSTALLING CAMSHAFTS

AND CYLINDER HEAD

Removing:

1.

Align lifting-platform pads beneath

jacking points and raise car.

2. Place protective covers on

fenders.

3. Disconnect ground lead from

battery

4. Disconnect breather hose for

toothed-belt cover from rear of

lower section of air filter. Detach

entire filter assembly and remove.

5.

Remove air-flow sensor and

disconnect support (M 8 bolt)

from intake manifold.

6.

Remove throttle-valve actuating

able complete with reversing

roller and holder. Remove oil

dipstick. Slacken hose clamps at

intake manifold, brake booster

and breather hose and remove.

7.

Remove cover of fuel-distribution

pipe. Slacken hose clamp for fuel

return line and disconnect hose.

Disconnect fuel feed while

countering.

15 - 106 Removing and Installing

Camshafts and Cylinder Head Printed in Germany

944 Engine/Cylinder Head, Valves

15

8.

Disconnect vacuum hose,

fuel-line-pressure damper

and fuel-distribution pipe

from intake manifold,

disconnect plug from idle

actuator, remove fuel rail with

injection valves and place to one

side.

9. Disconnect throttle-valve switch

connector. Unbolt intake manifold

from cylinder head and remove.

10.

Remove engine underguard. Open

coolant drain plug and catch

coolant in suitable container.

11.

Detach exhaust at

exhaust-manifold flange.

12.

Pull off spark-plug caps and

remove distributor cap. Slacken

hose clamp at ATF reservoir.

13.

Unbolt and remove upper and

lower toothed-belt covers,

front camshaft sprocket bracket

and cylinder-head cover.

14.

Turn engine in direction of

rotation until cylinder 1

ignition TDC is reached.

Printed in Germany - XIII, 1987 Removing and Installing

Camshafts and Cylinder Head

15 - 107

15 Engine/Cylinder Head, Valves 944

15.

Relieve tension of camshaft

toothed belt by slackening nut

A and bolt B, pressing

toothed-belt tensioner against

the pressure of the spring with

Special Tool 9200 and removing

toothed belt from camshaft

sprocket.

16.

Remove distributor rotor. Insert

3 temporary retaining bolts

M 5 x 20 to hold camshaft

sprocket to avoid upsetting

basic camshaft setting when

camshaft central bolt is

slackened.

17.

Slacken central bolt while

countering. Remove camshaft

sprocket.

18.

Remove rear bracket.

19.

Unbolt and remove chain

tensioner.

Note:

Chain-tensioner plunger is spring

loaded. When removing. compress

plunger and after removal hold in

this position with a piece of wire

or a retaining clamp.

15 - 108 Removing and Installing

Camshafts and Cylinder Head Printed in Germany

944 Engine/Cylinder Head and Valve Drive 15

20.

Remove bearing cover from cylinders

1 + 3.

Hold both camshafts in the bearings with

Special Tool 9226. Undo and remove front

double bearing bridge and bearing cover.

87 - 422

Note

The rear double bearing bridge may remain

on the cylinder head.

21.

Undo Special Tool evenly, remove both

camshafts with chain and lay together

on

one side.

22.

Undo cylinder head. Undo in sequence:

from outside to inside.

23.

Remove cylinder head.

Note

If oil has been mixed with water, the cylinder

head must be subjected to a thorough visual

inspection (hairline fractures). At the same

time, check the coating system for leaks.

Use

test unit VW 1274 above the expansion tank

for the teak test (max. 1 bar). The camshaft

cover must be removed for visual inspection.

Checking or adjusting camshaft sitting f. Model 89 onward

Printed in Germany - XIX, 1989 15 - 109

15 Engine/Cylinder Head and Valve Drive 944

Installing and tightening the cylinder head

Model 87 onward

Engine type M 44.40

Note

The cylinder head may be mounted with the

engine installed.

1.

Place the cylinder head gasket in the cer-

rect position.

2. Mount cylinder head

Tightening sequence:

87/420

Opposite to undoing sequence.

Tightening specifications for cylinder

head

Model 87 onward

Engine type M 44.40

1st stage

2nd stage

3rd stage

20 Nm

90° torque angle

Model 89 onward

Engine type M 44.41 (3.0 I)

Note

The cylinder head has been reinforced by

20

mm in the area of the bearing surfaces for

the

cylinder head nuts. This has altered the

tightening sequence.

Tightening specifications

Model 89 onward

Engine type M 44.41 (3.0 l)

1st stage

2nd stage

3rd stage

20 Nm

60° torque angle

90° torque angle

Note

Never use lubricant when fitting cylinder

head

nuts and washers. Apply a light film of

engine

oil to the stud thread only.

15 - 110 Installing and tightening the cylinder head

Printed in Germany - XXV, 1992

944 Engine/Cylinder Head, Valve Drive 15

Installing camshafts

1.

Turn engine in direction of rotation by ap-

prox. 45° before ignition TDC (cylinder

1).

2. Lay intake shaft and exhaust camshaft in

the timing chain.

3. Place both camshafts in the timing chain

so

that the cast lugs are alignedwith the

marked links of the chain. Oil the bearing

jounals and place in the bearings

carefully

together with the timing chain.

Note

The distance between the marking on the

intake camshaft and the markingon the

exhaust camshaft amounts to 7 outer chain

links; the distance betweenthe cast lugs

measures approx. 113 mm.

11838

4.

Fasten the camshafts to the cylinder

head

with assembly bridges SpecialTool 9248

together with the clamping bolt of Special

Tool 9226.

87/422

5.

Install the bearing bridges and bearing

cover af the camshaft. The

bearingbridges

and cover are production-matched to the

cylinder head and must alwaysbe

installed

as a set. Note the identification code and

pairing number.

Tightening torque for bearing bridges

and

cover 20 Nm.

11804

Installing camshafts

Printed in Germany - XVII, 1988 15 - 111

15 Engine/Cylinder Head, Valve Drive 944

11639

6.

Apply Loctite 574 to the sealing surfaces of

the front and rear double bearing bridges.

7. Use the assembly drift, Special Tool 9233

and pressure piece 9234 to drive the

sealing

ring into position at the drive end of the

camshaft. Lubricate the sealing lip before

assembly.

11794

Note

The timing chain must always be replaced

if

the valves have beendamaged by the

piston

as a result of a broken toothed belt.

A thorough visual inspection must be

made

of the sprockets and chain tensioner.

15 - 112 Installing camshafts

Printed in Germany - XVII, 1988

944 Engine/Cylinder Head, Valve Drive 15

Installing Camshaft Seal

1.

Place sealing washers in bearings and

install bearing bridge with Loctite 574.

Tightening torque 20 Nm (15 ftlb).

87/465

2.

After torquing the bearing bridge, install

sealing cover with the aid af Special Tool

9234

86/925

Engine installed

Note:

If the sealing cover af an engine leaks with

the engine installed, the procedure for

installing the cover is as follows:

1.

Place camshafts and sealing washers in

bearing.

2. Apply Loctite 574 to bearing bridge and

install. Place a 0.20 mm feeler gauge

between bearing bridge and cylinder

head

and tighten botts slightly by hand.

928/01

3.

Apply a light film af oil to sealing cover

and

press an by hand. Tighten bearing bridge

to 20 Nm (15 ftlb).

Installing Camshafts Seal

Printed in Germany - XVII, 1988 15 - 112a

15 Engine/Cylinder Head and Valve Drive 944

Camshaft

specifications Worldwide, Model 87

onward Worldwide, Model 89

onward

Engine type

Camshafts

Inlet shaft

Exhaust shaft

Identification code

On the rear

face

Timing

1 mm stroke, zero play

Inlet opens

Inlet closes

Exhaust opens

Exhaust closes

944 S

M 44.40

944.105.277.04

944.105.275.04

277.04

275.04

4° CS

40° CS

36° CS

4° CS

atter TDC

atter BDC

before BDC

before TDC

944 S 2

M 44.41 (3,0 l)

944.105.277.07

944.105.275.09

277.07

275.09

3° CS

47° CS

39° CS

7° CS

atter TDC

atter BDC

before BDC

before TDC

15 - 112b Camshafts specifikations

Printed in Germany - XIX, 1989

944 Engine/Cylinder Head, Valves

15

REMOVING AND INSTALLING CHAIN

TENSIONER

Removing

Remove hollow screws from cylinder

head and chain tensioner and

remove complete with oil line and

seals.

Note:

Chain-tensioner plunger is

spring-loaded. When removing,

compress plunger and hold in this

position with suitable retainer

(improvised tool).

Installing

1.

Chain tensioner can be installed

without removal of retaining

clamp.

2. The retaining clamp for the

chain-tensioner plunger must be

removed once the chain tensioner

is installed.

3.

When installing the oil delivery

line, install a sealing ring at

both ends of the two hollow

bolts. The check valve is in the

chain tensioner housing.

Tightening torque of hollow

bolts: 10 Nm (7 ftlb)

Printed in Germany - XIII, 1987 Removing and Installing

Chain Tensioner

15 - 113

15 944

This page are missing or blank in the book !

15 - 114

Blank page

944 Engine/Cylinder Head, Valves

15

TOOLS - CYLINDER HEAD (16-VALVE ENGINES)

No. Description Special Tool Remarks

1

2

3

Puller for valve stem

seals

Press-in tool for valve

stem seals

Valve spring assembly tool

9237

9225/1

9242

Or US 1020

+ US 1020/1

Printed in Germany - XIII, 1987 Tools - Cylinder Head

15 - 115

15 Engine/Cylinder Head, Valves 944

DISASSEMBLING AND ASSEMBLING CYLINDER HEAD (16-VALVE ENGINES)

15 - 116 Disassembling and Assembling Cylinder Head Printed in Germany

944 Engine/Cylinder Head, Valves

15

Note When: No. Description Qty.

Removing Installing

1

2

3

4

5

6

7

8

9

10

Hydraulic

valve tappet

Conical valve

keeper

Spring plate

Valve spring

set

Valve spring

support

Washer

Valve stem seal

Intake valve

Exhaust valve

Valve guide

16

32

16

X

16

8

16

Withdraw with a magnet,

do not mix up

Note number

Oil

Check correct

seating

Redetermine if

necessary

Always replace,

drive in with

press-in tool,

Special Tool

9225/1, oil sealing

lip, use drift

Oil valve stem

Printed in Germany - XIII, 1987 Disassembling and Assembling

Cylinder Head

15 - 117

15 Engine/Cylinder Head, Valve Drive 944

Cylinder Head (16 Valves)

Removing and installing valve springs

Tools

87/927

No.

Description Special tool Remarks

1

2

3

4

5

6

Assembly bridge

Lever arm

Magnetic removal head

Assembly head

Spacer

Screws

Supplier: Sauer Hamburg

Commercially available M 8 x 40

Note

If the cylinder head is installed, the lever arm must be angled more accutely.

15 - 118 Removing and installing valve springs

Printed in Germany - XVII, 1988

944 Engine/Cylinder Head, Valve Drive 15

Notes on assembly

Remove and install the valve springs with

the special tool supplied by Sauer

1.

Mount the assembly bridge on the

cylinder

head. Secure the cylinderhead to the

work

bench with a screw clamp to prevent

tilting.

2. Fasten the magnetic removal head to the

lever arm. Press the valve

springstogether

in the cylinder head and loosen the

conical valve keeper from the valve shaft

with a small screwdriver.

87/926

3.

All valve spring components can be

pulled

out with the magnetic removal head.

4. Fasten the assembly head to the lever

arm. Prags the tensioningarms toget her

and place the conical valve keepers in

the asssembly head.

87/926

5.

Place washer, valve spring support.

valve

springs and spring plate in the cylinder

head and prags together with the

assembly

head. A small up and down movement of

the lever arm allows the conical valve-

keepers to lock into place. This

movement

also positions the conicalvalve keepers

automatically in the correct location.

87/925

6.

When the conical valve keepers are

locked

in, the tensioning arms of the assembly

head point outwards.

Removing and installing valve springs

Printed in Germany - XVII, 1988 15 - 119

15 Engine/Cylinder Head, Valves 944

Remachining cylinder-head maling face

Checking cylinder head for distortion

Use a feeler gage an a straight edge or a

precision straight edge to check the maling

face of the cylinder head for distortion.

Permissible maling-face uneveness: 0.05

mm

Cylinder heads with distorted maling faces

can be remachined and reused. Permissible

rough atter finishing: 0.03 mm.

Remachining cylinder head

Do not remove mor material from the cylinder

head maling face than is necessary to

achieve a smooth surface. Max. machining

depth 146.6 mm.

Note on machining maling face:

Peak-to-valley = 0.015 mm

If the new-dimension tolerance is exceeded

during machining, a cylinder head gasket

with a thickness of 1.4 mm must be fitted.

Size new

Size worn = 147 +- 0.1 mm

= 146.6 mm

1126-15

Cylinder head refacing dimension and

identification

New dimension

Gasket

Identification

Refacing dimension

Gasket

Identification

: 147 +- 0.1 mm

: 1.1 mm

: none

: 146.8 to 146.6 mm

: 1.4 mm

: N

Identification "N"

To be embossed on exhaust side, between

cylinders no. 2 and 3, on the casting lug

below

the sealing face of the cylinder head cover.

Punch character height "N" = 6 mm

15 - 120 Remachining cylinder-heat mating face

Printed in Germany - XXV, 1992

944 Engine/Cylinder Head, Valves

15

NOTES ON ASSEMBLY

REMOVING AND INSTALLING VALVE

SPRINGS

Cylinder head removed

Remove and install valve springs

with US 1020 + US 1020/1.

REMOVING AND INSTALLING VALVE

SPRINGS

Cylinder head installed

Remove and install valve springs

with Special Tool 9242.

REMOVING VALVE STEM SEAL

Remove valve stem seal with Special

Tool 9237.

Printed in Germany - XIII, 1987 Removing and Installing

Valve Springs

Remove Valve Stem Seal

15 - 121

15 Engine/Cylinder Head, Valves 944

INSTALLING VALVE STEM SEAL

Note:

Always remember to place an 1 mm

thick washer on the cylinder-head

face before installing the valve

stem seal.

1.

Lubricate valve stem and install

shaft. Place an 1 mm thick washer

on cylinder-head face. Push drift

over valve stem. Lubricate

sealing lip of valve stem seal

and position on drift. Using

Special Tool 9225/1, carefully

and gently push seal as far as it

will go onto valve guide.

2. The valve stem seal is correctly

seated when Special Tool 9225/1

and washer make contact.

Note:

The assembly drifts are available

as spare parts.

15 - 122 Installing Valve Stem Seal Printed in Germany

944 Engine/Cylinder Head, Valve Drive 15

Checking the valve guides

1.

Clean the valve guides thoroughly.

2. Use a new valve to measure the tilt

play.

3. Mount bar gate holder VW 387 on the

cylinder head. The dial gaugemust be

aligned parallel to the valve disk.

15/2

15/3

4.

The tilt play is measured with 10 mm

valve

stroke (distance betweenthe valve disk

and

valve seat). Wear limit for intake and

exhaust guides = 0.80 mm.

Checking the valve guides

Printed in Germany - XVII, 1988 15 - 123

15 944

15 - 124 Blank page

944 Engine/Cylinder Head, Valve Drive 15

Replacing valve guides

Tools

87/918

No. Description Special tool Remarks

1

2

3

4

Ejection base

Plunger

Reamer

3120

See drawing

VW special tool

Replacing valve guides

Printed in Germany - XVII, 1988 15 - 125

15 Engine/Cylinder Head, Valve Drive 944

Drawing

Plunger to press out the valve guide

15 - 126 Replacing valve guides

Printed in Germany - XVII, 1988

944 Engine/Cylinder Head, Valve Drive 15

Drawing

Plunger to press out the valve guide

Plunger to press in the valve guide

Replacing valve guides

Printed in Germany - XVII, 1988 15 - 127

15 Engine, Cylinder Head, Valve Drive 944

Replacing the valve guides

1.

Clean and inspect the cylinder head. It is

inexpedient to replace the valve guides

in

cylinder heads where remachining is no

longer possible on the valve seats or

sealing areas.

2. Lay the cylinder head on the ejection

base.

3. Press out the valve guides from the

camshaft side to the combustionchamber

side with a press.

87/921

4.

Measure the bores in cylinder with an

internat measuring caliper.

87/919

5.

Machine the SP valve guide Part No.

944

104 327 51 (outer diameter 11.26 mm)

accordingly.

The pressing must amount to 0.06 - 0.8

mm

for intake and exhaust valve guides

Example

Bore in the cylinder head measures

11.020 mm. Machine the outside diameter of

the SP valve guide accordingly to 11.080 or

11.10 mm.

Note

A 1 mm thick washer must always be placed

on cylinder-head face before installing the

valve guide.

6.

Heat the cylinder head up to 170 °C

(338°

F). Apply a film of tallow tothe valve

guides.

Position with a light knock, align and.

from

the camshaftside, press into the cylinder

head as far as the stop with aplunger.

Attention

The temperature of 170 °C (338 °F). must

only be maintainedfor a maximum of 90

minutes.

15 - 128 Replacing the valve guides

Printed in Germany - XVII, 1988

944 Engine, Cylinder Head, Valve Drive 15

7.

Ream the valve guides with

Special Tool 3120

Proceed as follows:

The valve guides must always be reamed with

"petroleum" lubricant Withdraw the reamer

regularly to remove chips. Then finish-ream

the boreagain with a dry reamer.

87/920

8.

The valve seat rings must be remachined

alter replacing the valve guides. It is not

enough to grind in the valves with grinding

paste

Replacing the valve guides

Printed in Germany - XVII, 1988 15 - 129

15 Engine, Cylinder Head, Valve Drive 944

Checking the valve seat wear limit

1.

The valve seats in the 4-valve cylinder

heads can be remachined. At the same

time, the wear limit dimension must not

be exceeded as this would mean that the

hydraulic valve tappets may no longer

function correctly.

Wear dimension Intake valve Exhaust valve

As from Model 87 44.4 mm 43.4 mm

2.

This is measured with the valve to be

installed, from the end of the valve shaft to

the contact area af the valve spring

support

in the cylinder head.

11841

3.

The valve must be held firmly on the valve

seat for measurement.

15 - 130 Checking the valve seat wear limit

Printed in Germany - XVII, 1988

944 Engine, Cylinder Head, Valve Drive 15

Checking and remachining valve seats

Visuel inspection

1.

Check that the valve seat sits securely in

the

cylinder head.

2.

Check the contact pattern. If the valve

does make contact over the emire

surface of the valve seat. remiII the seat

slighdy.

Remachining

1.

Valve seats can be remachined, for

example. with the Neway valve milleror

the Hunger valve seat tuming tool.

2.

Remachine the valve seats with a 45°

seat milling cutter. Then machine the seat

to the prescribed width with a 60°

correction millingcutter. A 30° correction

milling cutter is not required.

Intake seat width 1.5 mm

Exhaust seat width

1.8 mm

1/05

3. Valve seat milling cutter. e.g.

Neway 234 45°

Neway 213 60°

11862

11865

Checking and remachining valve seats

Printed in Germany - XVII, 1988 15 - 131

15 Engine, Cylinder Head, Valve Drive 944

11864

4.

Valve seat turning tool, e.g. Hunger

VDSNL

1/45 I.K.

85/151

5.

After milling, grind in the valve seats

lightly

with grinding paste. Check the contact

pattern af the valve seat surface.

Valve dimensions

15/127

Valve dimensions 944 S

As from Model 87

Engine type M 44.40

Dimension Intake Exhaust

a

b

c

37 mm

6.97 mm

114.7 mm

45°

33 mm

6.94 mm

113.7 mm

45°

15 - 132 Checking and remachining valve seats

Printed in Germany - XVII, 1988

944 Engine, Cylinder Head and Valve Drive 15

Checking and adjusting installation

length of valve springs

Valve springs, Model 87 onward

Engine type M 44.40

Note

When selecting the valve-spring seat (own

construetion) always ensure that the valve-

spring seat is 2.0 + 0.2 mm thick.

1/03

Tool (own construetion)

Valve spring Sp No. 944.105.467.03

Auxiliary spring Sp No. 928.107.171.01

1.

Machine a recess of approx. 10 mm width

into valve-spring seat. Only install valve-

spring seat for measurement.

2.

Shorten the auxiliary spring to approx.

50 mm to ease assembly.

86/927

3.

Install valve and hold in valve seat. Insert

washer. valve-spring seat, auxiliary

spring

and valve-spring seat with machined

recess.

4:

Use Special Tool 9242 to fit the conical

valve keepers.

Checking and adjusting installation length of valve springs

Printed in Germany - XIX, 1989 15 - 133

15 Engine, Cylinder Head and Valve Drive 944

5.

Using a depth gauge, measure from the

top surface of the valve-spring seat,

vertically downwards through the recess

to the outer spring contact surface.

86/930

Installation length

Inlet valve

Exhaust valve 38.0 + 0.5 mm

37.0 + 0.5 mm

6.

The installation length can be adjusted

using shims.

7.

The valves must not be mixed up again

after measurement.

Valve spring, Model 89 onward

Engine type M 44.41 (3.0 l)

Note

A new type of valve spring has been

installed

in engine type M 44.41 (3.0 l) from Model 89

onward. The installation length remains

unchanged.

Installation lengths

Inlet valve

Exhaust valve 38.0 + 0.5 mm

37.0 + 0.5 mm

Carry out working procedure Checking and

adjusting installation length of valve springs

as described on Page 15 - 133.

15 - 134

Checking and adjusting installation length of valve springs

Printed in Germany - XIX, 1989

944 Engine/Lubrication

17

CHANGING ENGINE OIL AND ENGINE OIL FILTER (16-VALVE ENGINES)

Preconditioned:

Engine at operating temperature.

1.

Unscrew and remove oil filler cap.

2.

Unscrew oil drain plug from oil pan and

drain engine oil.

3.

Remove oil filter with oil-filter wrench,

Special Tool 9204. Catch remaining oil.

4.

Clean drain plug and never forget to

replace seal. Tightening torque: 50 Nm

(37 ftlb).

5.

Lightly oil gasket of oil filter, screw in by

hand until gasket makes contact, and turn

through one further turn to tighten. To

ensure that filter is correctly seated,

recheck with oil-filter wrench. Tightening

torque (for guidance): 20 Nm (14 ftlb).

6.

Pour in engine oil, run ergine to operating

temperature and check for leaks.

7.

Check oil level with engine switched off.

Printed in Germany - XIII, 1987 Changing Engine Oil

and Engine Oil Filter

17 - 101

17 Engine, Lubrication 944

Removing and installing the pressure reducing valve

Engine type M44.40

80/17

1 -

2 -

3 -

4 -

Se screw

Pressure reducing valve

O-ring

1. Remove the cylinder head cover and

undo

the set screw by 2 rums.

2. Ease the pressure reducing valve out of

the seat with a screwdriverand take out

upwards.

3. Replace the O-rings and apply a light film

of oil before installation.

4. Tighten the set screw carefully until you

can feel the stop, then tum back by 45°.

The screw must not be loose.

(Microencapsulated, renew if necessary).

17 - 102 Removing and installing the pressure reducing valve

Printed in Germany - XVII, 1988

944 Engine/Cooling

19

MIXING TABLE FOR COOLANT

(Average values)

Antifreeze

effective to Antifreeze Agent Water Antifreeze Agent Water

- 25° C

- 30° C

- 35° C

40%

45%

50%

60%

55%

50%

3.1 l

3.5 l

3.9 l

4.7 l

4.3 l

3.9 l

CHECKING HEATING AND COOLING SYSTEM

FOR LEAKS (16-VALVE ENGINES)

1.

Visual inspection for leaks.

2. Check routing of cooling and

heating hoses, look for signs of

porosity, swelling, cracks and

rubbing. Replace damaged hoses.

3. Retighten hose clamps.

Printed in Germany - XIII, 1987 Checking Cooling and Heating

System for Leaks 19 - 101

20 944

20 - 100 Blank Page

944 Fuel Supply

20

REPLACING FUEL FILTER (16-VALVE

ENGINES)

1.

Disconnect fuel lines, always counter

when slackening threaded connectors.

Catch fuel exiting from lines in a suitable

container.

2.

Slacken retaining clamp and remove fuel

filter.

3.

Install new filter. Direction of flow is as

indicated by the arrow.

CHECKING FUEL AND INJECTION LINES

FOR LEAKS AND LOOSE CONNECTIONS

1.

Visual inspection for leaks.

2.

Retighten union nuts and hose clamp.

Printed in Germany - XIII, 1987 Replacing Fuel Filter, Checking

Injection Lines for Leaks and

Loose Connections

20 - 101

20 Fuel Supply 944

CHECKING DELIVERY RATE OF FUEL PUMP

Precondition:

Fuel filter and power supply OK.

1.

Unbolt fuel return hose from pressure

regulator. Connect a length of

commercially available fuel hose and

place one end in a graduated cylinder

(capacity apprax. 1500 cc).

2.

Disconnect DME relay from central

electrics and, using a length of wire,

jumper terminals 30 and 87 b.

Allow fuel to flow into graduated cylinder for

30 seconds. Minimum delivery rate is 850

cc/30s, if necessary replace fuel pump.

20 - 102 Checking Delivery Rate of Fuel Pump Printed in Germany

944 Fuel Supply

20

FUEL SYSTEM LINE ROUTING (16-VALVE ENGINES)

'87 MODELS ONWARD

ENGINE TYPE M 44.40

1 Fuel pump

2 Fuel filter

3 Fuel collector tube

4 Pressure damper

5 Pressure regulator

A Air flow sensor

B Throttle valve housing

C Intake tube

D Idle actuator

E Intake jet pump

F Electric tank breather valve

a from fuel tank

b to fuel tank

c from activated charcoal canister

d to brake unit

Printed in Germany - XIII, 1987 Fuel System Line Routing

(16-Valve Engines) 20 - 103

24 944

24 - 100 Blank Page

944 L-Jetronic Fuel Injection

24

REPLACING AIR FILTER ELEMENT

(16-VALVE ENGINES)

1.

Use a screwdriver to remove

mounting screws and remove

upper part of air filter.

3.

Remove filter element and

clean inside of lower half of

air-filter housing with a

lint-free cloth

4. Insert filter element, place

housing cover in position and

tighten mounting screws. Check

that upper part of air filter

is correctly seated.

CHECKING INTAKE AIR GUIDE AND

CRANKCASE BREATHER HOSES FOR

LEAKS

AND LOOSE CONNECTIONS

1.

Check all hoses of intake system

for loose connections

2. Retighten hose clamps.

Printed in Germany - XIII, 1987 Replacing Air Filter Element,

Checking intake Air Guide Hoses 24 - 101

24 Air Flow Controlled Fuelinjection 944

Testing and adjusting specifications

Model 87 onward

Engine type M 44.40/41 (3.0 I)

Test Specifikation Remarks

Electric fuel

pump

Min. delivery

rate 850 cm3/30 s

Fuel pressure

(engine stationary)

DEE relay

jumpered

3.8 +- 0.2 bar

Checking value at

idle

approx. 3.3 +- 0.2

bar

Leak test

min. pressure after

20 Min.

2.0 bar

Idle speed

rpm

CO values %

ppm

without catalytic

converter

840 +- 40 **

0.5...1.5

<= 300

with

catalytic

converte

840 +- 40 **

0.4...1.2 *

<= 300 *

**

Idle speed

can only now be

checked. Idle adjust-

ment no longer

applies.

*

Measured upstream at

catalytic converter and

Lambda HC value

probe connector not

separated

CO adjustment no

longer applies.

Note

Carry out working procedure checking delivery rate of fuel pump and checking fuel

pressure as described an Pages 20 - 102 and 24 - 103 respectively.

Tightening torque for cap nut 12 Nm.

24 - 102 Testing and adjusting specifications

Printed in Germany - XIX, 1989

944 L-Jetronic Fuel Injection

24

CHECKING FUEL PRESSURE

TOOLS

No. Description Special Tool Remarks

Pressure gage with hose

from pressure tester P 378 or VW 1318

Printed in Germany - XIII, 1987 Checking Fuel Pressure

24 - 103

24 L-Jetronic Fuel Injection 944

CHECKING FUEL PRESSURE

1.

Slacken and remove capped nut on

test connection of fuel

distribution line.

Note:

Be careful that sealing ball does

not fall out when capped nut is

removed.

2.

Connect pressure gage with hose

from pressure tester P 378 or VW

1318 to test connection.

3.

Disconnect DME relay from central

electrics and jumper terminals 30

and 87 b with a length of

electric wire. Fuel pump must now

run.

4.

Control value:

Engine stopped 3.8 +- 0.2 bar

(DME relay jumpered)

Engine idling, approx. 3.3 bar

5. Tightening torque of capped nut:

22 Nm (16 ftlb)

24 - 104 Checking Fuel Pressure Printed in Germany

944 Air Flow Controlled Fuel Injection 24

Checking idle speed and CO-

with catalytic converter

Model 87 onward

Engine type M 44.40/41 (3.0 l)

Note

It is no longer possible to adjust idle speed

or

CO on vehicles with catalytic converters. The

Lambda probe remains connected while

chekking idle speed and CO.

Checking preconditions

Engine in perfect mechanical condition. Con-

sumers must be switched off during checks.

Carry out checks as quickly as possible to

ensure that the intake paths do not heat up

thus falsifying the CO value. Ambient

temperature 15 - 35° C.

1.

Fit standard exhaust adapter to the test

connector of the catalytic converter.

Engine type M 44.40

86/463

Engine type M 44.41 (3.0 l)

173-24

2.

Warm engine up to operating

temperature.

(70 - 90° C oil temperature.) Use the oil-

temperature tester, Special TooIs 9122

and 9122/2.

85/114

3.

Do not separate the connection for the

Lambda probe. Connect CO tester and

separate speedometer according to the

manufacturer's specifications.

CO reference value 0.4...1.2%

Idle speed 840 +- 40 rpm

Checking idle speed and CO- with catalytic converter

Printed in Germany - XIX, 1989 24 - 105

24 Air Flow Controlled Fuel Injection 944

Checking idle speed and CO

without catalytic converter

Model 87 onward

Engine type M 44.40/41 (3.0 l)

Note

It is no longer possible to adjust the idle

speed. The throttle valve connector

adjustment therefore no longer applies.

Idle/CO adjustment

Adjustment preconditions

Engine in perfect mechanical conditions.

Consumers must be switched off during

adjustment work. Carry out adjustment as

quickly as possible to ensure that the intake

paths do not heat up thus falsifying the CO

value. Ambient temperature 15 - 35° C.

1.

Warm engine up to operating

temperature.

(70 - 90°C oii temperature). Use oil

tempe-

rature tester, Special Tools 9122 and

9122/2.

2.

Check CO value. If the CO value is not

within the prescribed tolerances. correct

the setting at the air-flow sensor. Remove

the sealing plug in the access bore to

the CO adjusting screw.

Engine type M 44.40

Standard screwdriver for 3 mm Allen screw.

Engine type M 44.41 (3.0 l)

Standard angled screwdriver for 5 mm

Allen screw.

Illustration shows engine type M 44.40

86/512

CO setting: 0.5...1.5 %

Turn to the right - richer mixture

Turn to the left - leaner mixture

Checking idle speed.

1.

Connect separate speedometer

according

to manufacturer's specifications.

Idle speed 840 +- 40 rpm

24 - 106 Checking idle speed and CO- with catalytic converte

Printed in Germany - XIX, 1989

944 Air Flow Controlled Fuel Injection 24

Replacing air filter insert

Model 89 onward

Engine type M 44.41 (3.0 l)

1.

Replace front end plate. Refer to 944

Workshop Manual Page 50 - 5.

2.

Undo retaining clips and remove housing

cover with filter insert.

3.

Clean inside of filter housing with lint-free

cloth.

4.

Install new filter insert. Observe

installation

position. Arrow or TOP-OBEN marking

points towards the engine.

172 - 24

Checking idle speed and CO- with catalytic converte

Printed in Germany - XIX, 1989 24 - 107

26 944

26 - 100 Blank Page

944 Exhaust System

26

CHECKING TIGHTNESS OF EXHAUST SYSTEM FLANGES (16-VALVE ENGINES)

1.

Check tightness of exhaust

flanges and check entire exhaust

system for leaks.

2. Check tightness of hex nuts on

exhaust manifold/cylinder head

flange.

3. Check tightness of all flange

connectians in exhaust system,

together with oxygen sensor and

exhaust extractian tube.

4.

Check tightness af bolts in

primary muffler (catalytic

converter)/secondary muffler

flange. Check exhaust-system

hangers.

Tightening torques of nuts and

bolts:

M 8

M10 20 + 2 Nm (14 + 1.4 ftlb)

40 + 5 Nm (30 + 3.6 ftlb)

Printed in Germany - XIII, 1987 Checking Tightness of Exhaust

System Flanges

26 - 101

28 944

28 - 100 Blank Page

944 Ignition System

28

EQUIPMENT TABlE

Ignition Coil

Type/Model Version Remarks

944 S 944 602 115 00

Bosch No.

0 221 118 322

Without series

resistors

Distributor (Cap)

Type/Model Version Remarks

944 S 928 602 211 01

Bosch No.

1 235 522 395

Only high-tension

distribution

Spark plugs

Type/Model Version Remarks

944 S Bosch WR 7 DC Spark gap

0.7 + 0.1 mm

Ignition trigger box

Type/Model Version Remarks

944 S 928 602 706 01

Bosch No.

0 227 100 124

Printed in Germany - XIII, 1987 Equipment Table

28 - 101

28 Ignition System 944

DME control unit

Type/Model Version Remarks

944 S Mod. '87 944.618.124.00

944.618.124.01 M 44.40

Spare part

944 S Mod. '88 944.618.124.01 M 44.40

Hall probe for knock sensors

Type/Model Version Remarks

944 S 944.606.170.01

Knock sensor

Type/Model Version Remarks

944 S 944.606.145.00 Tightening torque

= 20 Nm (14 ftlb),

use specified

mounting bolt

(without washer)

28 - 102

Printed in Germany - XXV, 1992

944 Egnition System

28

DME CONTROL UNIT CODING, 944 S, '87 MODELS ONWARD

1 - 944.612.525.01

2 - 928.607.421.00

3 - 928.607.422.00

4 - 944.612.522.00

1 - Plug for characteristic-map switch

2 - Plug for variant switch

Country Characteristic-map switch,

ter. 54 Varient switch, ter. 39

USA, rest of

world with

catalytic

converters

California,

Japan 928.607.421.00

EC, without

catalytic

converters

928.607.422.00

Sweden 944.612.522.00

Australia 944.612.525.01

Printed in Germany - XVII, 1988 DME Control Unit Coding,

944 S '87 Models Onward

28 - 103

28 Ignition System 944

REPLACING SPARK PLUGS, 944 S

1.

Pull off spark plug caps.

2. Unscrew spark plugs with

commercially available wrench. A

spark-plug wrench is supplied as

part of the car's toolkit.

Tightening torque: 25 - 30 Nm

(18 - 22 ftlb).

28 - 104 Replacing Spark Plugs Printed in Germany

944 Ignition System 28

Equipment tabte 89 models onward

Engine type M 44.41 (3.0 l)

Ignition Coll

Type/Model Version Remarks

944 S 2 944 602 115 00

Bosch No.

0 221 118 322

without series resistors

Distributor (Cap)

Type/Model Version Remarks

944 S 2 928 602 211 01

Bosch No.

1 235 522 395

Only high-tension distribution

Spark plugs

Type/Model Version Remarks

944 S 2 Bosch WR 5 DC Spark gap

0,7 + 0,1 mm

Ignition trigger box

Type/Model Version Remarks

944 S 2 928 602 706 01

Bosch No.

0 227 100 124

Equipment table 89 models onward

Printed in Germany - XXV, 1992 28 - 105

28 Ignition System 944

DME Control unit

Type/Model Version Remarks

944 S 2 Mod. ´89/90

944 S 2 Mod. ´91 944.618.124.02

944.618.124.05

Hall probe for knock sensors

Type/Model Version Remarks

944 S 2 944.606.170.01

Knock sensor

Type/Model Version Remarks

944 S 2 944.606.145.00 Tightening torque

= 20 Nm (14 ftlb),

use specified

mounting bolt

(without washer)

28 - 106 Equipment table 89 models onward

Printed in Germany - XXV, 1992

944 Ignition System, Diagnosis 28

Coding - DEE control unit 944 S 2, Model 89 onwards

86/746 B

86/733

1 - 928.607.421.00

2 - 928.607.422.00 1 - not used

2 - connector for variant switch

Country Variant switch

USA, rest of world with

catalytic convertor

California, Japan 928.607.421.00

Rest of world without

catalytic converter

928.607.422.00

Coding - DEE control unit 944 S 2, Model 89 onwards

Printed in Germany - XIX, 1989 28 - 107

DME-Diagnosis / Troubleshooting

Dr. Ing. h.c. F. Porsche Aktiengesellschaft

944 S/944 S2 Fuel System - Electronic Control 24/28

Test Point Description Page

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Precautions

Important Vehicle Information

Testing Requirements

Effects of Faults (Cross Reference List)

DME Control Unit Plug Connections

Power Supply

Idle Speed Contact

Full Load Contact

Engine Temperature Sensor

Air Flow Sensor

Idle Speed Control Activation

Oxygen Regulation Stop

Oxygen Sensor

Intake Air Temperature Sensor

Knock Sensor I

Knock Sensor II

Control Unit Faulty

Hall Signal

Control Unit Faulty

DME Relays

Tank Venting Valve

Check Engine Waming Lamp

Fuel Pressure

Intake System Leaks

Ground and Plug Connections

Speed/Reference Mark Sender

Ignition and Final Stage

Fuel Injectors - Injection Control Unit

Alternator / Regulator

Leads K and L

CO and Idle Speed Test

Coding of Control Unit

Check-Engine-Lamp

2

3

4

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

24

25

28

29

30

31

32

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 1

24/28 Fuel System - Electronic Control 944 S/944 S2

Precautions

Greater demands of modern engines on the ignition systems and a desire for freedom from

maintenance had led to the introduction of electronic ignition systems in standard production

some time ago already. Normally the ignition power of electronic systems (almost all makes)

will be greater than that of conventional systems and evan greater power can be expected in

the future. This places electronic ignition systems in a power range, where touching current

carrying parts or terminats could be dangerous to lite (both primary and secondary circuits).

In conjunction with this matter we must point out that there must always be conformance with

safety regulations and legislation of a pertinent country when working on or testing ignition

systems. The ignition (ignition or source of power) must always be switched off when working

on the ignition system.

Sample Jobs:

Connecting engine testers, for example:

timing light, dwell angle/speed tester, oscilloscope, etc..

Replacing ignition components, for example:

spark plugs, ignition coil, distributor, ignition leads, etc..

The above mentioned dangerous voltage will be present in the entire system should it be

necessary to switch on the ignition for ignition tests or engine adjustments.

Consequently there is not onty danger on the various components of an ignition system (such

as, for example, distributor, ignition coil, control units, ignition tackle), but also on wire

harnesses, plug connections and testers.

D 24/28 - 2 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Important Vehicle Information

Always turn off the ignition or disconnect the battery for resistance tests (if not, the tester

could be destroyed).

Always disconnect the speed sender plug for compression tests (if not, there could be

dangerous high tension and damaged insulation on the ignition coil, high tension distributor

and ignition leads).

Never replace a specified ignition coil (see order number) with a different ignition coil.

Never connect a suppression capacitor on ignition coil terminals 1 and 15.

Never connect ignition coil terminal 1 on ground for the burglar alarm (ignition coil and

control unit could be destroyed).

Never connect battery + or a test lamp on ignition coil terminal 1 (control unit could be

destroyed).

Never disconnect the ignition lead between ignition coil terminal 4 and high tension

distributor terminal 4 during operation.

Avoid voltage flashover from ignition coil terminal 4 to ignition coil terminals 1 and 15

(control unit could be destroyed).

To avoid destruction of the control unit, the secondary circuit of the ignition system must be

suppressed with at least 4 k-ohms, whereby the original distributor rotor with 1 k-ohm

suppression resistance must be installed.

Disconnect DME control unit and ignition final stage plugs only atter turning off the ignition.

Flashover or disruptive discharge in the area of the high tension distributor cap (poor

insulation) could destroy the control unit.

Never disconnect the battery while the engine is running.

Mixing up battery pole connections could lead to destruction of the ignition final stage,

ignition coil and DME control unit.

Outside starting of the engine with more than 16 volts or a boost battery charger is

forbidden.

Always conform with accident prevention regulations when working on fuel systems.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 3

24/28 Fuel System - Electronic Control 944 S/944 S2

Equipnient Required for DME Tests:

-

Diagnostics tester 9288 (9268) with

connecting leads

-

1 oscilloscope approved by Porsche

-

1 digital display multimeter with an internal

resistance of at least 10 M-ohms

-

1 Bosch L-Jetronic test lead, Bosch No.

1684 463 093 (check read for correct

polarity in plugs)

-

2 control unit plug test leads (local

manufacture) fitted with 2 flat male plugs,

'N 17.457.2, in order to avoid damage on

plug pins in the control unit plug while

testing

-

2 adapter test leads, consisting of 4 plug

connectors, N 017.483.1, soldered with 2

approx. 150 mm lang leads

-

1 three-pin test lead (e.g. VW VAG 1501)

-

2 control unit plug test leads (local

manufacture) fitted with 4 flat male plugs,

N 17.457.2

Test leads must always be used for

testing!

-

All sender and ignition timing signals of

Porsche models can be checked with the

engine reglers recommended by Porsche.

Instructions for connection of testers on a

car will be different depending on the

make, so that it will always be necessary

to conform with the instructions supplied

with a pertinent tester.

Sender Signals Which Can Be Checked

With An Oscilloscope:

-

Speed sender signal

-

Injection ( ) signals

-

Idle speed control activation signal

-

Hall sender signal

-

Ignition trigger signal to ignition final stage

-

Tank venting activation signal

as well as:

-

Reed switch signal (speedometer)

-

ABS wheel sensor signals

D 24/28 - 4 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Diagnosable DME Control Unit

Self-

diagnosis with a fault memory, with which it is possible to detect and store certain injection.

ignition and knock regulating system faults, is integrated in the DME control unit of 944 S cars

beginning with 1988 models.

The DME control unit has a permanent positive connection to prevent cancellation of detected

and stored faults by turning off the ignition. Detected faults remain stored in the memory for at

least 50 engine starts (exception: idle speed switch interruption faults).

Important!

If the DME control unit plug or battery is disconnected, the fault memory and system adaptation

will be cancelled.

Tester Connections:

A 12-pin plug, which leads out of the DME wire harness in the passenger's footwell to the right

above the DME control unit, is provided for diagnosing in cars since 1988 models. 9268

Flashing Code Testers can be connected on this plug.

A 19-pin plug replaces the 12-pin plug beginning with 1990 (L) models. Either a 9288 System

Tester or the Flashing Code Tester (via adapter leads 9268/2) can be connected on this plug.

Operation of the testers is explained in the instructions supplied with the testers.

Note:

A pertinent test point is supplemented by a corresponding fault flashing code of Tester 9268.

Example:

Test Point 2 = idle speed contact (1-12)

Second digit display:

"1" fault exists

"2" fault does not exist

The following actual engine data can be read direct in the "actual value" menu with a 9288

System Tester beginning with the version 2.0 tester module status.

Intake air temperature

Ignition timing

Oxygen sensor voltage

Version code

Idle drive pulse duty factor

Engine temperature

Engine speed

Power supply

Air flow sensor signal

Load signal

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 5

24/28 Fuel System - Electronic Control 944 S/944 S2

This DME 944 S Diagnosing/Troubleshooting Plan is based on the contents of the fault

memory.

Paths not included in self-diagnosis can be diagnosed with conventional equipment (Test

Points 17-25. see Fault List).

Troubleshooting requires that the person performing the tests

is familiar with the location of components, the function and technical interconnections of the

systems being tested (model information).

can read and evaluate Porsche wiring diagrams.

knows the functions of circuits and relays, and

is capable of using testers, such as the oscilloscpe, voltmeter, ohmmeter and ammeter, as

well as evaluating the test results.

Important!

A fault text in the display (Fault List and Flashing Code) does not always indicate a fault in the

pertinent component, but could also concern t

he corresponding control unit or connecting leads

(paths) between the component and control unit.

Troubleshooting on a running engine in the form of disconnection of plugs, etc. must not be

carried out prior to reading the fault memory, since such action could be stored as faults in the

fault memory.

9288 System Tester Information

Displayed in Tester

Fault does not exist, this could mean:

Fault not existing at time of testing (loose contact).

Remedy: visual inspection of path (connection).

Conditions, with which the fault is tested. ara not the same as the conditions, with which the

fault had occurred.

Remedy: conform with conditions displayed in the tester.

Signal Not Plausible:

Signal of the monitored component does not fit in the tolerance range of the value calculated in

the control unit.

D 24/28 - 6 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

This page are missing or blank in the book !

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 7

24/28 Fuel System - Electronic Control 944 S/944 S2

This page are missing or blank in the book !

D 24/28 - 8 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Fault, Fault Code Possible Causes, Elimination, Remarks

Test

Point

1a

Power

supply for

DME

control unit

(V)

a) Perm. pos. (B + )

Fault memory is cancelled, if there is

no B +.

Testing:

Connect a voltmeter on terminal 24 (-) and terminal 18 ( +) of the control unit plug

with help of test leads.

Display: battery voltage

No display: check current flow and ground paths according to the wiring diagram.

Test Point

1b

Power

supply for

DME

control unit

(V)

too high /

too low

Fault Code

1_11

b) Power supply via DME relay

Connect a voltmeter on terminal 24 (-) and terminal 37 (+) of the control unit plug

with help of test leads. Turn on ignition.

Display: battery voltage

No display: check current flow path according to the wiring diagram.

Remarks:

Cars with burglar alarm: check power supply from ignition lock via burglar alarm

control unit to terminal 86 af the DME relay according to the wiring diagram.

Cars without burglar alarm: check pin bridges on plug (provided for installation

of a burglar alarm control unit).

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 9

24/28 Fuel System - Electronic Control 944 S/944 S2

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 2:

Idle speed

contact ( )

Ground short

Fault Code 1_12

Check via circuit input test with 9288 System Tester or 9268 Tester.

Select test step and operate accelerator pedal.

9288 Display:

Idle speed contact made

Idle speed contact broken

9268 Display: 1332 (idle speed contact made)

0000 (idle speed contact broken)

No Display:

Pull off plug on DME control unit.

Connect ohmmeter between terminal 52 and terminal 24 with help of test

leads.

Display:

Throttle valve closed

Throttle valve opened to gap of

< 10

> 1° =

If the value of the idle speed contact is not reached in this test, the test

should be repeated direct on the throttle valve switch as described below.

Pull off plug on throttle valve switch. Connect ohmmeter between terminals 1

and 2 of the throttle valve switch with help of test leads.

Display:

Throttle valve closed

Throttle valve opened to gap of

< 10

> 1° =

Idle speed

contact ( )

Break

Fault Code 1_15

Testing same as described for ground short

(fault stored in memory as of 1991 models).

Check for correct adjustment, correcting if necessary.

Cause, for example, could be an incorrectly adjusted throttle valve switch or

accelerator cable.

D 24/28 - 10 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 3

Full load contact ( )

Ground short

Fault Code 1_13

Check via circuit input test with a 9288 System Tester or 9268

Tester.

Select test step and operate accelerator pedal.

9288 Display:

9268 Display:

Full load contact broken

Full load contact made

1333 (tull load contact broken)

0000 (full load contact made)

No Display:

Connect ohmmeter on terminal 53 and terminal 24 of the

disconnected DME control unit plug with help of test leads.

Display:

Throttle valve closed

Throttle valve opened about

2/3rd of full gap

< 10

If the value of the full load contact is not reached in this test, the

test should be repeated direct on the throttle valve switch as

described below.

Pull off plug on throttle valve switch. Connect ohmmeter

between terminal 3 and terminal 2 of the throttle valve switch

with help of test leads.

Display:

Throttle valve closed

Throttle valve opened about

2/3rd af full gap

< 10

Remarks:

If the full load contact fails, the control unit produces a load

threshhold via the air flow sensor. Value below this load

threshold same as switch broken or above load threshold same

as switch made.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 11

24/28 Fuel System - Electronic Control 944 S/944 S2

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 4

Engine tamp. sensor

(NTC II/ )

Fault Code 1_14

Engine temperature can be read direct from the "actual value"

menu with a 9288 System Tester.

No Plausible Display:

Connect ohmmeter on terminal 45 and terminal 24 of the

disconnected DME control unit plug with help af test leads.

Display at:

0°C =

15 - 30°C =

40°C =

80°C =

100°C =

4.4 - 6.8 k

1.4 - 3.6 k

1.0 - 1.3 k

250 - 390

160 - 210

Test direct on the engine temperature sensor, if the values are

not reached.

Note: Temperature sensor II sends information about the engine

temperature to the control unit. It is used to provide a rich fuer/air

mix-ture after a cold start or during warm-up.

Break ( ):

DME control unit of the 944 S selects a resistance value, which

is stored in the control unit's memory and is approximately equal

to that of an engine at operating temperature. There is no

enrichment from a faulty NTC II when the engine is warm

(emergency running program). This results in starting problems

when the engine is cold (no cold start enrichment).

Short (0 ):

No engine pickup, too lean and stopping of engine in cold state.

No effects in operating temperature state.

Replacement value is applicable to both types of fault!

D 24/28 - 12 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Fault, Fault Code Possible Causes, Elimination, Remarks

Test

Point 5a:

Air flow

sensor

(V/ )

Fault

Code

1_21

The ratio between Up (potentiometer voltage) and Uv (power supply voltage) can

be read in the "actual value" menu with a 9288 System Tester.

When opening the air flow sensor plate the ratio must be about 0.0 to 1. If not:

a) Power supply voltage

Connect a voltmeter on terminal 3 and terminal 4 of the disconnected air flow

sensor plug with help of test leads. Turn on ignition.

Display: 5 +- 0.3 volts

Test

Point

5b:

b) Voltage drop on air flow sensor plate potentiometer (V)

Take off air cleaner connecting hose. Connect pin 3 of the disconnected air flow

sensor plug with air flow sensor plug terminal 3 and pin 4 with air flow sensor plug

terminal 4 with help of test leads.

Connect a voltmeter on air flow sensor terminal 2 and terminal 4 (turn on ignition).

Display: approx. 250 - 260 m V

It must be possible to move the air flow sensor plate easily and without hesitation.

Observe the voltmeter's display at the same time. Voltage jump of voltage drop

should not be observed while the air flow sensor plate is opening or closing.

Display with air flow sensor prate in full load position:

approx. 4.60 volts.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXIV, 1991 D 24/28 - 13

24/28 Fuel System - Electronic Control 944 S/944 S2

Fault, Fault Code Possible Causes, Elimination, Remarks

Turn off ignition and reconnect plug if the voltage values have been reached.

Remarks:

Control unit produces replacement values in case of air flow sensor failure

(emergency running program).

Injection signal

from nominal air of the idle speed volumetric efficiency control

for idle or a constant injection signal for partial load and full load ranges.

Test Point 6:

Idle speed

control (V)

Fault Code

1_22 only S2

Element Activation Menu

If pulse cannot be heard, check:

Power supply

Connect a voltmeter on terminal 2 and

ground of the disconnected idle speed

control plug.

Turn on ignition.

Display: battery voltage

No display:

Check power supply according to the wiring diagram.

Control signal test

The pulse duty factor in % can be read direct in the "actual value" menu with a

9288 System Tester.

Function test: Switch on electric power consumers with engine running at idle

speed. The pulse duty factor must change and the idle speed must remain

constant.

If not:

D 24/28 - 14 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Fault, Fault Code Possible Causes, Elimination, Remarks

Connect two-pin DME test lead (Bosch No. 1 684 463 093) between the speed

control and plug.

Connect and adjust engine tester to supplied operating instructions.

Make sure that electric lead connections do not have contact with vehicle ground

(danger of short).

Displayed with the engine running:

Frequency: approx. 100 Hz.

Replace the idle speed control it the pulse cannot be heard in spite of correct

power supply and received signal.

Test Point

7

Oxygen

regulation

on stop

Fault Code

1_23

Oxygen regulation cannot work in its regulating range in case at disturbances in

air/fuel mixture; for example: too lean because of excessive air or too rich

because of a sticking fuel injector. It then moves against the stop.

Test 1:

Check CO level with the engine running and CO

tester connected (between 0.4 and 1.2 %).

too lean:

Check intake system for leaks

(Test Point 19).

too rich:

Check system pressure (Test Point 18).

Check fuel injectors for leaks (Test Point 18).

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 15

24/28 Fuel System - Electronic Control 944 S/944 S2

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point 8:

Oxygen sensor

(V)

(sensor signal)

Fault Code 1_24

Sensor signal test

Sensor voltage can be read direct in the "actual value" menu with a 9288

System Tester.

If not:

Disconnect oxygen sensor plug. Connect a digital display

voltmeter on the sensor end test connection (sensor

voltage signal) and ground.

Start and run engine warm so that the oxygen sensor

reaches its operating temperature. A change in the

voltage signal must be displayed when the mixture is

richer, e.g. by accelerating.

Display on voltmeter:

approx. 150 mV - 900 mV (depending on composition of mixture)

Remarks:

If the control unit recognizes an oxygen) sensor voltage signal of more than

1 V or less than 0.1 V, the control unit will switch over to operation without

oxygen sensor (short or break).

If regulation does not work and the sensor voltage signal is okay, check the

coding of the control unit before replacing the control unit.

Test Point 9

Air temperature

sensor

NTC I ( )

Fault Code 1_25

Intake air temperature can be read direct in the "actual value" menu with a

9288 System Tester.

If not or when a non-plausible value is displayed:

Connect an ohmmeter on terminal 44 and terminal 26 of the disconnected

DME control unit plug.

Display at:

0°C =

15-30°C =

40°C =

4.4-6.8 k

1.4-3.6 k

1-1.3 k

D 24/28 - 16 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Fault, Fault Code Possible Causes, Elimination, Remarks

If no display: Disconnect plug on air flow sensor. Connect an ohmmeter on air

flow sensor terminals 1 and 4 with help of test leads. Display: same as above.

Note: In case of a break, there will be a replacement value equal to an intake

air temperature of 20° C (emergency running program).

Test Point 10

Knock sensor

I

Fault Code

1_31

Knock sensor I: Knock signal not plausible. Check:

-

Installation of knock sensor (check tightening torque and type of screw).

Wire harness and plug connections according to wiring diagram.

Reconnecting sensors eliminates contact resistance.

Whether coolant or other liquids are in area of the knock sensor.

Replace knock sensor.

Ignition timing retarded by 6° on crankshaft in case of a faulty knock sensor.

Test Point 11

Knock sensor

II

Fault Code

1_32

Knock sensor II: Knock signal not plausible. Check:

-

Installation of knock sensor (check tightening torque and type of screw).

Wire harness and plug connections according to wiring diagram.

Reconnecting sensors eliminates contact resistance.

Whether coolant or other liquids are in area of the knock sensor.

Replace knock sensor.

Ignition timing retarded by 6" on crankshaft in case of a faulty knock sensor.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 17

24/28 Fuel System - Electronic Control 944 S/944 S2

Fault, Fault Code Possible Causes, Elimination, Remarks

Test Point

12:

Control

unit

(knock

computer)

Fault Code

1_33

Ignition timing is retarded 6° in case of this fault.

Replace control unit.

Test Point

13:

Hall signal

Fault Code

1_34

Disconnect plug on cylinder head behind the camshaft drive gear and connect a

three-pin adapter lead (VW 1501) inbetween to check the Hall signal. Connect

oscilloscope positive and negative test leads on terminals 1 and 2 of the adapter

lead. Start the engine.

This signal should be displayed when the Hall system is okay:

Ignition timing will be retarded approximately 6° in all speed ranges, if the DME

control unit recognizes that the Hall signal is missing.

Protective circuit test:

Turn off ignition. Disconnect Hall plug. Start the engine. Idle speed ignition timing

will adjust itself to approximately 4° before TDC (944 S). There must be a certain

load signal from the air flow sensor in case of 944 S2 cars.

Test Point

14:

Control

unit faulty

Fault Code

1_41

Replace control unit.

D 24/28 - 18 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Fault, Fault Code Possible Causes, Elimination, Remarks

Test

Point 15:

DME

relay

(fuel

pump) (V)

Start the engine - fuel pump must run during engine starting.

It not:

Turn off ignition. Disconnect control unit plug. Connect terminal 3 and terminal 24

on the control unit plug with help of a test lead.

Turn on ignition - the pump must run!

It not:

Check current flow and ground paths of DME relay and fuel pump according to the

wiring diagram.

Test

Point 16:

Tank

venting

valve (V)

Fault

Code

1_43

(not 944

S)

Electric valve (for brake booster) will be opened more or less long depending on

the engine load when an engine having operating temperature is running. The

opened time is determined by a ground pulse from the control unit.

a) Activation test

Activate the tank venting valve in the "element activation" menu of the tester. It a

pulse is not heard, check power supply to terminal 1 of the electromagnetic valve

plug according to the wiring diagram.

b) Control signal test

Install DME test read (Bosch No. 1 684 463 093) between the electromagnetic

valve and plug connection. Connect and adjust engine tester according to the

supplied operating instructions.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 19

24/28 Fuel System - Electronic Control 944 S/944 S2

Fault, Fault Code Possible Causes, Elimination, Remarks

Tank venting valve is not activated permanently.

Test must be performed within 7 minutes after starting an engine having

operating temperature (interrupt tank venting valve activation approx. 75

seconds afterward and then continue).

Start engine and accelerate. This must be displayed in the tester for an engine

at operating temperature:

Signal will be wider as the air flow rate increases!

Check path according to the wiring diagram if there is no signal.

Replace control unit if necessary.

Test Point

17:

Check

Engine

warning

lamp

Fault Code

1_45

(California as

of

1991 models)

A ground signal from control unit plug terminal 22 goes to and switches on the

"Check Engine Lamp", if a component influencing emission control fails.

If the "Check Engine" warning lamp fails, this fault is stored in the fault

memory.

Check by supplying ground to control unit plug terminal 22 and turning on the

ignition.

Always replace a faulty display lamp with a specified lamp.

D 24/28 - 20 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Test Point 18: Fuel Pressure

Fuel collection pipe has a test

connection at left front. Unscrew

cap nut of the test connection.

Important! Inserted ball seal could

fall out!

Connect P 378 pressure tester on

the test connection. Start the

engine. Vacuum on pressure

regulator at idle speed:

Test pressure: 3.3 +- 0.2. bar

Hot starting problems:

Check with the engine stopped and fuel pump

running, without vacuum on the pressure regulator

(this requires removing the DME relay and bridging

terminals 87b and 30):

Test pressure: 3.8 +- 0.2 bar

-

Stop fuel pump. Read pressure on the pres

sure tester (specitication: 3.8 +- 0.2 bar).

- Max. permissible pressure drop on warm

engine: 0.5 bar in 30 minutes.

- It the pressure drops below the specitied

value, proceed as described below.

Build up pressure again by switching on the fuel pump briefly. Remove return pipe on the

pressure regulator (fuel pump must not be switched on).

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 21

24/28 Fuel System - Electronic Control 944 S/944 S2

Test Point 19: Intake System leaks

Check all connections after the air flow

sensor for leaks. Remove upper air cleaner

section. Apply Special Tool 9264/4 on the air

flow sensor and produce approx. 0.5 bar

pressure in the intake system. Leaks will

cause the pressure in the system to drop

quickly.

(944 S: shut the safety pressure valve for

crankcase breathing.)

Remarks:

Flashing Fault Code 1_23 (oxygen

regulation on stop) is displayed in cars with

oxygen regulation and very large leakage in

the intake system (for example: intake pipe

gasket).

Test Point 20: Ground Connections (V)

Ground read (2 x) from wire harness to

engine block.

battery ground lead on clutch bell

housing (engine ground) and on body

(body ground next to battery).

Ignition final stage ground on side

member at left front.

Fuel pump ground on rear lock cross

wall behind the spare wheel.

Are ground connections tight and without

corrosion? Loosen, clean and retighten

ground connections as specified.

Caution!

Never start the engine as long as the

ground lead between the body and

engine is disconnected!

This would destroy the control unit

immediately!.

D 24/28 - 22 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Plug Connections

Are all plugs connected correctly, not loose

and not corroded?

Disconnect plugs and check whether pins

and terminals of plugs are bent or corroded.

55-pin plug an DME control unit (behind

floor plate in the front passenger's

footwell).

14-pin plug in engine compartment next

to the brake booster.

3-pin plug for reference mark/speed

sender and 3-pin plug for oxygen sensor

behind the intake pipe for cylinder no. 4

(first remove cover an the fuel ring-pipe).

3-pin plug an throttle valve switch.

2-pin plug on electromagnetic valve for

tank venting (an brake boaster).

4-pin plug an air flow sensor.

2-

pin plug an NTC II (temperature sensor

is screwed in the engine block above the

left compensating shaft near cylinder no.

1).

7-pin plug on ignition final stage in the

engine compartment at front left.

3-pin Hall sender plug (behind the

camshaft drive gear).

2-pin plug for knock sensor I (between in

take pipes for cylinder no. 1 and 2).

2-

pin plug for knock sensor II (between in

take pipes for cylinder no. 3 and 4).

2-pin plugon idle speed control (between

intake pipes for cylinder no. 2 and 3).

944 S2: between cylinder no. 1 and 2.

Plug for fuel injector ballast resistors (in

engine compartment at rear right next to

the plug for the brake pad wear

indicator).

2-pin plugs on each of the four fuel

injectors.

Because 944 S cars are supplied worldwide

since 1987 models with only one standard

control unit and said control unit is coded

accordingly depending an country

equipment, this coding must be checked in

case of complaint.

A 2-pin or 3-pin plug leads out at the DME

wire harness near the plug receptacle, in

order to be able to call the different curve

families.

Power is supplied to the DME control unit of

a 944 S via terminal 30 (battery +) in

addition to via ignition lock terminal 15.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 23

24/28 Fuel System - Electronic Control 944 S/944 S2

Test Point 21: Speed/Reference

Mark Sender

This test can only be performed with an oscillo-

scope. Connect and adjust a workshop oscillo-

scope according to the supplied operating

instructions for this purpose.

Connect the positive tester lead via a test lead

on control unit plug terminal 47 and negative

tester lead via a test lead on control unit plug

terminal 48.

Crank engine with the starter motor. Sinusoidal

oscillation of at least 3 volts (speed pulse) and

an applied higher amplitude (reference mark)

must be displayed on the screen.

If the voltage signal is too small (< 3 V), the

distance between the sender and gear ring

could be adjusted incorrectly.

Sender distance: Between gear ring and

sender: 0.8 +- 0.3 mm.

1 - Speed signal

2 - Reference mark signal

D 24/28 - 24 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

No display:

Disconnect plug of speed sender on plug

plate in the engine compartment. Connect

tester leads on middle and outside pins of

the plug on the sender end of the plug with

help of test leads (terminals 1 and 2, pin

end). Start the engine. Sinusoidal oscillation

must be displayed on the screen.

Speed sender plug

Remarks:

The display must remain unchanged after

supplying ground to connection 3.

If not, check power flow, spacing and

condition of the sender.

Test Point 22: Ignition

a) Secondary ignition display

Adjust secondary ignition display an the

oscilloscope. Connect tester leads according

to the supplied operating instructions.

Note:

If a fault is displayed for all cylinders, it is in

the primary or secondary circuit from the

ignition coil to the distributor rotor. If a fault is

displayed for one cylinder, this fault is

located after the distributor rotor.

Primary resistor:

Secondary

resistor:

Term.1 + 15 = 0.4-0.6

Term.1 + 4 = 5-7.2 k

b) Spark plug connectors ( )

Suppression resistor: 3 k

Visual inspection for damage or traces of

burning.

c) Distributor

Distributor rotor, distributor cap: suppression

resistor = each 1 k .

Visual inspection for damage, dirt or wrong

location.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 25

24/28 Fuel System - Electronic Control 944 S/944 S2

d) Ignition timing test

Ignition timing is checked with the engine at

operating temperature.

Ignition timing and engine speed can be

read direct in the "actual value" menu with a

9288 System Tester.

Test value: (944 S + 944 S2)

At 840 +- 40 rpm 10° +- 3°

e) Activation of high tension end

(if ignition sparks are not triggered)

Ignition triggering signal can be simulated for

fast troubleshooting of the ignition end. This

requires connecting the oscilloscope term. 4

tester lead on the ignition lead betw. ignition

cail and high tension distributor (term. 4).

Disconnect DME control unit plug.

Turn on ignition.

If battery voltage is new supplied

intermittently to terminal 1 of the control unit

with help of a test lead (e.g. control unit plug

term. 18), a high tension peak must be

displayed on the oscilloscope each time

(ignition triggering).

If there is no signal, check:

-

Power supply to ignition final stage and

ignition coil.

-

Ground connection for ignition final stage

(ground point on left front side member).

- Plug connections on ignition final stage,

ignition coil and high tension distributor.

-

Components responsible for high tension

(for example: ignition coil, ignition leads,

spark plug connectors, etc.).

- Power flow in lead between control unit

plug and ignition final stage term. 5.

D 24/28 - 26 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

f) Ignition final stage control signal test

Connect DME control unit plug.

Connect oscilloscope's positive tester lead

on terminal 5 and negative tester lead on

terminal 2 of the disconnected final stage

plug.

Operate starter motor.

Oscilloscope should display the control

signal of the DME control unit.

Very important:

Coat the baseplate with a heat conducting

paste prior to installation of the ignition final

stage. Keep heat conducting paste off of

painted parts.

Heat conducting paste:

Bosch No. 5 942 860 003.

1 - Final stage

2 - Baseplate

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 27

24/28 Fuel System - Electronic Control 944 S/944 S2

Test Point 23: Fuel Injectors -

Injection Timing (V/ )

Element activation menu:

If a pulse is not heard, check:

a) Power supply

Pull off injector plug. Connect voltmeter on

injector plug terminal 2 and ground with help

of test leads. Turn on ignition.

Display: battery voltage

If there is no dispiay:

Disconnect 5-pin plug of fuel injector ballast

resistors. Connect voltmeter between

terminal 3 (terminal sleeve end) and ground.

Turn on ignition.

If battery voltage is displayed, Turn off

ignition and pull off all plugs on fuel injectors.

Check power flow and resistance between

the S-pin plug of ballast resistors and

terminal 2 of each fuel injector plug with an

ohmmeter.

Resistance of each ballast resistor = 6

Check current path according to the wiring

diagram if battery voltage is not displayed.

b) Coil resistanee test of fuel injectors

Pull off injector plugs. Check coil resistance

on the contacts of the fuel injectors with an

ohmmeter.

Test value: 2 - 3

c) Injection final stage

Adjust oscilloscope according to the

supplied operating instructions. Connect

Bosch test lead (1 684 463 093) between

fuel injector and plug. Connect tester leads

on Bosch lead according to the supplied

operating instructions.

Caution:

Tester leads must not have any contact

with ground.

Start the engine. These displays must

appear in the oscilloscope if the injection

final stage is working perfectly and test

connections are correct.

Starter speed

Remarks:

If the engine cannot be started or the idle

speed drops, change tester connections on

the Bosch lead and check tester

adjustment.

D 24/28 - 28 DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989

944 S/944 S2 Fuel System - Electronic Control 24/28

Test Point 24: Alternator, Regulator

Misfiring of the engine could be caused by

the peak voltage of the alternator.

Take drive belt off of the alternator. Start the

engine.

Check alternator and regulator if the

disturbances have been eliminated.

Test Point 25: Leads K and L

Connections for diagnosing between the

DME control unit and fasters are made with

both leads K and L Check the folIowing

points when diagnosing is not possible.

1. Power flow test (see wiring diagram)

Lead L: Pin 7 (19-pin diagnostics socket) -

Pin 13 (DME plug)

Lead K: Pin 8 (19-pin diagnostics socket) -

Pin 55 (DME plug)

2. Ground short test (see wiring diagram)

Lead L: Voltage on Pin 7 (19-pin diagnostics

socket) must be > 8 V with the ignition

turned on.

Lead K: Voltage on pin 8 (19-pin diagnostics

socket) must be > 8 V with the ignition

turned on.

Possible Causes of Fault:

-

Ground short or break in wiring or plug

connections.

- Faulty control unit, which is connected on

these leads (could be any diagnosable

control unit; does not always have to be

the DME control unit).

Checking: Pull off plugs on diagnosable

control units one after the other until there

is

> 8 V. Replace fault-eausing control unit.

-

Tester faulty.

- Power supply lacking on diagnostics

socket.

- Ground supply lacking on diagnostics

socket.

Information for idle speed and idle speed

CO test:

a) Idle speed

944 S engines have adaptive idle speed

volumetric efficiency regulation since 1987

modeIs. This means that the idle speed of all

versions does not have to be adjusted. The

system of cars with adaptive idle speed

volumetric efficiency regulation should be

adapted each time the DME control unit had

been disconnected on permanent positive or

after each inspection.

Idle speed control value for engine at

operating temperature:

840 +- 40 rpm

b) Idle speed CO of cars without catalytic

converter

CO level is still adjusted on the CO adjusting

screw in the air flow sensor.

Requirements:

-

Engine at operating temperature.

- Engine and ignition in perfect running

condition.

- All electric consumers switched off.

- CO tester at operating temperature,

calibrated and adjusted correctly.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 29

24/28 Fuel System - Electronic Control 944 S/944 S2

Adjusting value: 0.5 - 1.5 % CO

at 840 +- 40 rpm and ignition timing of

10° +- 3° before TDC.

Adapt the system after adjusting the CO level.

An adapter plug (911.612.422.8) must be con-

nected on the oxygen sensor connecting lead

of cars without a catalytic converter, in order

to avoid diffusion (see wiring diagram).

c) Idle speed CO of cars with catalytic

converter

In addition to adaptation of the idle speed

there is also adaptation of the idle speed CO

level in these cars, so that it is only necessary

to check the actual state in such cars.

Requirements:

-

Engine at operating temperature.

- Engine and ignition in perfect running

condition.

- All electric consumers switched off.

- CO tester at operating temperature,

calibrated and adjusted correctly.

- Oxygen sensor plug connected.

Test value: 0.4 - 1.2 % CO

at 840 +- 40 rpm and ignition timing of

10° +- 3° before TOC.

Afterwards the engine must be run at least

10 minutes after disconnection of the

control unit plug or disconnection of the

battery, before it will be possible to recheck

these values. In addition, the system must

be adapted.

D 24/28 - 30 DME - Diagnosing/Troubleshooting

Printed In Germany - XXII, 1990

944 S/944 S2 Fuel System - Electronic Control 24/28

Coding of Control Unit - 944 S

Pertinent curve families are integrated in the DME control unit, in order to be able to comply

with the legislation of different countries. They can be read direct in the "actual value" menu

with a 9288 System Tester.

One each 2-pin and 3-pin plug, which are bridged differently depending on the country version,

lead out of the DME wire harness to call these curve families.

Country Curve Family Switch

2 Pins Version Switch

3 Pins

USA Federal States

FAG M 298

Oxygen sensor

- -

USA Califomia

Japan

Oxygen sensor

- Bridge against

battery voltage

928.607.421.00

ECE - Bridge against grd.

928.607.422.00

Sweden - Resistance

6.8 k against grd.

944.612.522.00

Australia

Oxygen sensor Bridge against ground

944.612.515.00 -

DME - Diagnosing/Troubleshooting

Printed In Germany - XXI, 1989 D 24/28 - 31

24/28 Fuel System - Electronic Control 944 S/944 S2

Coding af Control Unit - 944 S 2

Country Curve Family Switch

2 Pins Version Switch

3 Pins

All with cat. conv. - -

Califomia, Japan - Bridge against

battery +

928.607.421.00

All without cat. conv. - Bridge against grd.

928.607.422.000

As from model year '91, the code for California and Japan is being deleted (identical

worldwide).

D 24/28 - 32 DME - Diagnosing/Troubleshooting

Printed In Germany - XXII, 1990

944 S/944 S2 Fuel System - Electronic Control 24/28

Check-Engine Lamp

(Malfunction Indicator Light M.I.L)

As from model year '91, Califomian legislation prescribes a waming lamp which lights up if a

part relevant to the exhaust gas fails.

As a function check of the warning lamp, it lights up when the ignition is switched on and goes

out once the engine is running when this is started without depressing the accelerator.

The waming lamp has a flashing code to indicate a defective fault path.

To trigger off the flashing code, fully depress the accelerator pedal with the engine off and the

ignition on for 3 seconds until the Malfunction Indicator Lamp flashes. Then remove foot from

accelerator.

If no fault is recorded, i.e. no warning came from the indicator light, there appears the flashing

code

1500

no fault.

= Lamp on o = Lamp off

If the waming light did indicate a warning, i.e. there is a fault, there appears a flashing code,

e.g.

1124

Oxygen sensor

The flashing code is listed in the Diagnosing/Troubleshooting plan on page D 24/28-7.

The fault can also be read direct using System Tester 9288. After a repair the fault memory

must be erased using the System Tester.

DME - Diagnosing/Troubleshooting

Printed In Germany - XXII, 1990 D 24/28 - 33

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