Bosch No 0280161008

EZ Battery Reconditioning Method

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Fuel Pressure Regulator

928.110.198.01

Bosch No. 0280.160.215

Heated Wire Air Flow Sensor

NTC Temperature Sensor

(Double Func.)

Throttle Switch

Auxiliary Air Regulator

928.606.141.00

Bosch No. 0280.214.001

928.606.126.00

Bosch No. 0280.130.032

931.606.119.00

Bosch No. 0280.120.301

928.606.102.00

Bosch No. 0280.140.228

Vacuum Control Switzerland, Sweden, Australia (Manual Transm.)

930.110.173.00

Bosch No. 0280.160.302

Electric Air Valve

944.606.215.00

Bosch No. 0280.141.012

Electric Fuel Injectors

928.606.119.00

Bosch No. 0280.150.252

LH-Jetronic Control Unit

928.618.123.00

Bosch No. 0280.002.501

LH-JETRONIC AIR FLOW LAYOUT -928 S - R. o. W. - 1984 Models Engine Type 28-21/22

Bosch Auxiliary Air Regulator Hose Mount

1 - Intake air distributor

2 — Throttle housing

3 - Heated wire air flow sensor

7 — Electronic ignition control unit

8 — Electric air valve (air conditioner)

9 — Auxiliary air regulator

10 — Blowoff switching valve

11 — Check valve a — Temperature sensor I (intake air) for ignition P — Auxiliary air pump

LH-JETRONIC FUEL FLOW LAYOUT -928 S - R. o. W. - 1984 Models Engine Type 28-21/22

Bosch 406 Temp Sensor Location

2 - Fuel filter

3 — Pressure damper

5 — Fuel line with test connection

6 — Fuel injectors

7 — Pressure regulator

10 — Throttle housing

11 — Blowoff switching valve

12 - Temperature sensor II

LH-JETRONIC

Fuel Injection Tu3

No.

Description

Gty.

Note When: Removing Installing

Special Instructions

1

Bolt

3

2

Washer

3

3

Multiple pin plug LH control unit

1

Make sure plug engages securely

4

LH control unit

1

5

Control unit holder

1

6

Plug connector

8

7

Bolt

8

8

Washer

8

9

Distributing injection tube

2

10

Hose sleeve

8

11

Thrust plate

8

12

Fuel injector

8

13

Hose clamp

4

14

Hose

2

15

Elbow hose

2

16

Pressure regulator

2

17

Fuel line

1

18

Fuel line

1

19

Fuel line

1

20

Fuel line

1

21

Fuel line (feed)

1

No.

Description

Qty.

Installing

Special Instructions

22

Nut

1

23

Washer

1

24

Bolt

1

25

Pipe clamp

1

26

Holder

1

27

Elbow hose

1

28

Pressure damper

1

29

Nut

1

30

Washer

31

Nut

2

32

Washer

2

33

Holder

1

34

Fuel line

1

35

Fuel line

1

36

Fuel cooler

1

see page 24 -126

37

Hose clamp

4

38

Hose

1

39

Hose

1

40

Plug connector

1

41

Auxiliary air regulator

1

42

Plug connector

1

43

Throttle switch

1

44

Bolt

4

No.

Description

Qty.

Note When: Removing Installing

Special Instructions

45

Washer

4

46

Throttle housing

1

47

O-ring

48

Hose clamp

2

49

Connecting hose

1

50

Plug connector

1

51

Air flow sensor

1

52

O-ring (dust guard)

1

53

O-ring

1

54

Air guide housing

1

55

Seal

1

56

Temperature sensor I

1

57

Plug connector

1

58

Plug connector

1

59

Temperature sensor

1

60

Seal

1

61

Y-adapter

3

62

Plug connector for centra! electric

1

— Engine Tester with oscilloscope, e. g. 1010/1019, Bosch Mot 300/400

— Multiple tester (internal resistance at least 20 Kohm/V)

— Adapter line (Bosch "L-Jetronic" No. 1684 463 093)

— Pressure gauge with hose from pressure tester P 378

— Two test lines (made locally) for measuring on multiple pin plugs of control units and plug connectors with same type of contact (flat contacts)

1 — Highly flexible line

2 — Alligator clips (standard)

- Two adapters — test lines (made locally)

1 — Highly flexible line, approx. 10 cm long

2 — Insulating hose

3 - Flat contact N 17.182.2

LOCATION OF COMPONENTS

Electronic Fuel Injector Line Adapter

1 — Pressure damper

2 — Pressure regulator (two)

5 — Throttle switch

6 — Auxiliary air regulator

8 — Temperature sensor 11

11 — Fuel injectors, right

12 — Blowoff switching valve

13 — Ignition control unit

14 — Ignition coils

15 — Speed/reference mark sensors

17 — TDC sensor test connection

18 — Fuel pressure test connection

19 - Distributor

CENTRAL ELECTRIC POWER SUPPLY FOR LH / ELECTRONIC IGNITION

Conj Sensor Tdc

rrinrrrrrrrrr

1 - Electronic ignition relay VIII (power supply for electronic ignition and LH control units)

2 - LH-Jetronic relay XVI (power supply for LH control unit and air flow sensor)

3 — Fuel pump relay XVII (power supply for fuel pump, auxiliary air regulator and fuel injectors)

4 — Fuse no. 13 = fuel pump, auxiliary air regulator

5 — Plug X, red (power supply for electronic ignition/LH)

Testi ng Conditions

LH-Jetronic

Possible Causes of Defects

Engine in good operating condition

Battery charged

CJ cn 3

T3 C

Ol C

tu 3

c tu

JD T3

"O

to m

"03

See Test Point

10 11

Engine does not start Engine hard to start Erratic idling Poor pickup Misfiring

High fuel consumption Poor power output Engine hesitation

X = Check with suitable tester

TEST POINT 1

Checking Ground and Plug Connections

1.2 If battery voltage is not displayed, pull off relay XVI and bridge terminals 30 and 78.

Recheck voltage on LH multiple pin plug between terminals 9 and 5.

TEST POINT 2

Power Supply for LH Contro Unit and Fuel Pump

2. Fuel Pump

The fuel pump relay is activated negatively by the LH control unit.

1. LH Control Unit

Switch off ignition and pull off multiple pin plug on LH control unit.

1.1 Switch on ignition.

Measure voltage on multiple pin plug between terminals 9 and 5. Specification: battery voltage. If value deviates from specification, measure voltage on plug X connected on central electric board between terminal 8 and ground.

2.1 Connect terminal 17 on disconnected LH control unit plug on ground with a piece of wire.

Fuel pump relay should be activated and fuel pump must run.

If pump does not run, check fuse no. 13 and relay XVII activation as well as fuel pump relay.

3. Checking Control Signal for Electronic Ignition to LH Control Unit

4

1 1

1-1

3

■x1

2

1 1

1

1 1

Pull off multiple pin plug on LH control unit; leave plug on electronic ignition control unit.

3.1 Connect positive test lead of oscilloscope on terminal 1 and negative test lead on ground.

Specification: battery voltage

Oscilloscope should display following control signal.

1 2 3 4 5 6

If no signal is displayed, check power flow from terminal 16 of electronic ignition control unit plug to terminal 1 of LH control unit plug.

If power flow is okay, replace electronic ignition control unit.

TEST POINT 3

LH Air Flow Sensor

1. Take off upper air cleaner housing and filter element.

2. Pull lower air cleaner housing and air flow sensor out of air guide housing.

Pull off relay XVI for this purpose and bridge terminals 30 and 87.

Specification: battery voltage.

4. Measure resistance for idle mixture position.

Connect ohmmeter on terminals 6 and 3 of air flow sensor.

5. Connect ohmmeter on terminals 5 and 3 of air flow sensor.

3. Pull off multiple pin plug on air flow sensor.

Measure voltage between terminals 4 and 2 (positive) on disconnected plug.

6. Checking "Free Burning" of Heated Wire

6.1 Visually inspect

— plug connection and contacts,

— wire grid for damage and

— heated wire for breaks.

Heated wire must glow about 1 second after waiting approx. 4 seconds.

Check activation and wires in case of malfunction,

(LH plug terminal 8 to air flow sensor terminal 1).

6.2 Install air flow sensor with lower air cleaner housing.

Coat O-ring in air guide housing with silicone for this purpose.

Connect plugs on air flow sensor and temperature sensor.

Push in air flow sensor carefully.

6.3 Do not install filter element and upper air cleaner housing.

Run engine having operating temperature at approx. 2,000 rpm and then switch off ignition.

Observe heated wire with help of a mirror.

TEST POINT 4

Temperature Sensor II (Engine Temperature)

1. Check plug connection on temperature sensor II for tight fit and clean contacts.

379 Switch

2. Connect ohmmeter on terminals 2 and 5 of disconnected LH multiple pin plug.

Specifications:

0 °C/ 32 °F = 4.4-6.8 kH 15 to 30 °C/59 to 86 °F = 1.4 - 3.6 ki2 40 °C/ 104 °F = 0.9 -1.3 kft 60 °C/ 140 °F = 480 - 720 i2 80 °C/ 176 °F = 250- 390 ft

If specified values are not reached, repeat same tests on the temperature sensor direct.

jifeidÉlH

Note:

Two independent temperature sensors are installed in the temperature sensor housing.

Connect tester on only one contact of the sensor and a second test lead on ground.

Temperature sensor II provides the LH control unit with information on the instantaneous engine temperature. It enriches the fuel/air mixture for cold starting and engine warm-up.

In case of interruption (inf. ohms): excessively rich mixture, engine will not run in warm state and cannot be started.

In case of short circuit (0 ohm): mixture too lean, no pickup in cold state.

In case of interruption, wires could be bridged for emergency operation of the car.

TEST POINT 5

Throttle Switch.

1. Idle Speed Contact

Pull off multiple pin plugs on LH and electronic ignition control units.

1.1 Connect ohmmeter between terminals 3 and 5 on LH plug.

Specifications:

throttle closed = 0 ohm throttle opened = inf. ohms

Switching over must take place already with a throttle gap of approx. 1

2. Full Load Contact

2.1 Connect ohmmeter between terminals 12 and 5 on LH plug.

Specifications:

throttle closed = inf. ohms throttle in full load pos. = 0 ohm

Switching point is after approx. 3/4 throttle travel.

Make tests direct on throttle switch, if switching points are not reached.

Ohm Resistor Connect Battery 2032

TEST POINT 6

2- Idle speed contact 18 = Ground 3 = Full load contact

1. Checking Fuel Injectors

If engine can be operated, pull off plugs on injectors separately. If fuel injectors are okay, engine speed should drop each time.

If engine cannot be operated, measure voltage on one plug of injectors against ground.

One of both terminals should have battery voltage.

Measure coil resistance of fuel injectors.

Specification: 15 — 17.5 ohms (+15 . . . 30 °C/+ 59 . . .86 °F),

Note:

If idle speed switch has a break, there will be no coasting shutoff.

If idle speed switch has a short circuit, there will be a single cutout at high idle speed.

If full load switch has a break, there will be no full load enrichment.

If full load switch has a short circuit, enrichment will be too early and consequently fuel consumption too high.

2. Checking Injection Timing

Adjust oscilloscope according to instructions supplied with tester. Connect adapter line (Bosch "L-Jetronic" No. 1 684 463 093) between one fuel injector and corresponding plug.

Caution!

Tester leads must not have contact with ground.

Start engine. If injection timing is working correctly, the oscilloscope will display the following oscillographs.

STARTER SPEED

IDLE SPEED

ACCELERATION

DECELERATION

I

I

If engine does not start or the idle speed drops, exchange test connections on adapter line and check tester adjustment.

TEST POINT 7

Auxiliary Air Regulator

1. The auxiliary air regulator will be closed in heated state.

Squeeze air hose tight — engine speed may only drop slightly.

2. Pull off plug on auxiliary air regulator and measure voltage between both terminals.

Specification: battery voltage.

3. Measure resistance on auxiliary air regulator.

Specification: 10 ... 45 ohms.

TEST POINT 8

CO and Idle Speed Adjustment

TEST POINT 9

Leaks in Intake System

1. Remove air intake hoses.

2. Take off upper air cleaner housing and remove hose on blow-off switching valve.

3. Unscrew unlosable hexagon head screws (13 mm wrench size) in lower air cleaner housing and remove lower housing with heated wire air flow sensor. Pull off both multiple pin plugs.

Hho Vacuum Inlet Diesel

4. Unscrew heated wire air flow sensor on lower air cleaner housing and plug air inlet opening, e. g. with dust cap of original spare part package and heated wire air flow sensor.

Hexagonal Bar Pin Valves

5. Install lower air cleaner housing with air flow sensor.

6. Build up approx. 0.5 bar pressure.

7. Spray leak detecting spray on all connections. Bubbles will be produced at leaking points.

TEST POINT 10 Fuel Pressure

1. Unscrew cap nut on injection line. Note:

Be careful that sealing ball does not fall out when removing the cap nut. Catch escaping fuel.

2. Connect pressure tester P 378.

Pressure Fuel P378 Porsche 924

3. Start engine and measure fuel pressure at idle speed.

Specification: approx. 2.0 bar.

Pull off vacuum hose on left pressure regulator.

4. If fuel pressure deviates from specified values, slowly squeeze return line with a clamp applied at rear next to the fuel level transmitter.

TEST POINT 11

Alternator/Regulator

Bosch Fuel Injection

Peak voltage of the alternator could cause engine misfiring.

2. Start engine. If misfiring is eliminated, check alternator and regulator.

1. Remove drive belt and alternator.

If pressure rises to less than 4 bar, check fuel filter or, if necessary, replace fuel pump.

5. If engine cannot be operated, pull off relay XVII and bridge terminals 30 and 87.

Fuel pump must run. Specification: 2.3 . . . 2.7 bar.

TESTING OXYGEN SENSOR OPERATION, UP TO '86 MODELS

Brief test

If CO value does not change, there is a fault in either the oxygen sensor or the LH control unit.

Precondition:

- Engine at operating temperature.

- Ideal speed correctly adjusted.

- Exhaust tester connected to extraction point in engine compartment.

1.Disconnect oxygen sensor plug, wait until state of equilibrium is reached and note CO value.

Testing sensor voltage

¡.Precondition as for the "brief test"

2.Disconnect oxygen sensor plug.

3.Connect voltmeter to sensor half of plug and earth

390 Vacuum Lines

2.Disconnect vacuum line from fuel pressure regulator.

The CO reading must show a considerable increase.

3.Reconnect oxygen sensor plug. The CO value must return to the specified 0.6 + 0.2%.

4.The voltage must be in the 0.1 V - 1.0 V range (depending on level of oxygen in the exhaust).

Voltage characteristic of oxygen sensor for working temperature of 600°C.

Rich mixture Lean mixture (air deficiency) (excessive air)

Testing lambda control function l.Test precondition as for "brief test".

2.Disconnect oxygen sensor plug.

3.With a length of cable, briefly connect cable of control-unit side of plug to ground.

The CO value must increase.

If there is no change in the CO value check connection to LH control unit, if necessary replace control unit.

TESTING AND ADJUSTING SPECIFICATIONS FOR LH-JETRONIC — TYPE 928 S Rest of World

Beginning with 1984 Models Engine Type M 28.21/22

Test Point

Specifications

Remarks

Electric fuel pump Delivery rate

at least 1350 cc/30 sec.

Fuel pressure (engine stopped) Fuel pump bridged

Check value for idle

2.5 + 0.2 bar approx.2 bar

Min. pressure after 20 minutes

1 bar

Idle adjustments Idle speed <rpm)

Switzerland, Sweden

ADJUSTING IDLE SPEED AND CO - beginning with 1984 models Engine Type M 28.21/22

TOOLS

No.

Description

Special Too!

Remarks

2

CO adjusting tool Oil temperature tester

9187 9122

ADJUSTING IDLE SPEED AND CO

Note: Requirement:

Engine in perfect mechanical condition.

Make adjustments as quickly as possible to avoid excessive heat in intake ports and consequently wrong CO values.

1. Take off right air intake hose.

2. Disconnect auxiliary air pump hose on air pipe and insert a suitable plug in open air pipe (e. g. rubber grommet for doors, Part No. 999.703.163.40).

3. Install air intake hose.

4. Run engine to operating temperature (oil temperature approx. 80 to 90 °C/ 176 to 194 °F).

Use Special Tool 9122 to measure oil temperature.

Porsche 924 Tacho Spiral

5. Connect CO tester and separate tachometer to supplier's instructions.

6. Turn control screw or bypass screw on throttle housing, until speed of

700 + 50 rpm is reached.

Rb25 Idle Auxiliary Air Unit Wiring

Note:

Use separate tachometer from tester or similar.

7. Adjust fuel/air mixture. Guide Special Tool 9187 into adjusting bore of heated wire air flow sensor and turn idle speed potentiometer accordingly.

Pictures Tools Separate Mixtures

Turning clockwise = richer mixture. Turning counterclockwise = leaner mixture.

CO specifications: 0.5 - 1.5 % R. o. W. 0.5 - 1.0 % Australia,

Switzerland, Sweden

8. Remove plug in air pipe and reconnect hose.

REMOVING AND INSTALLING HEATED WlRE AlR FLOW SENSOR

Removing

1. Remove air intake hoses.

2. Take off upper air cleaner housing and remove hose on blowoff switching valve.

2. Insert heated wire air flow sensor that access to adjusting bore for idle speed potentiometer with Special Tool 9187 is guaranteed.

Align air flow sensor if necessary.

3. Unscrew uniosable hexagon head screws (13 mm wrench size) in lower air cleaner housing and remove lower housing with heated wire air flow sensor.

4. Pull off both multiple pin plugs.

3. Install and mount lower air cleaner housing and then tighten bottom hose clamp.

5. Loosen bottom hose clamp and take heated wire air flow sensor off of lower air cleaner housing.

Installing

1. Check 0- ring in air guide housing for damage and correct fit. Lubricate 0 ring with silicone grease, e. g. Bosch Ft 2v2.

REMOVING AND INSTALLING FUEL COOLER

Removing

1. Discharge air conditioner as described in Group 87 of Repair Manual 928.

Note:

Conform with safety precautions for handling refrigerants.

2. Disconnect battery.

5. Remove fuel cooler.

a) First unscrew right refrigerant line coupling completely, while holding on hexagon of line.

b) Unscrew both fuel line connections on fuel cooler, while holding on cooler each time.

c) Unscrew bracket for fuel cooler.

d) Unscrew left refrigerant line coupling, while holding on hexagon of line.

3. Take off upper air cleaner housing and filter element.

Pull off hose on blowoff switching valve and unscrew unlosable hexagon head screws (13 mm wrench size) in lower air cleaner housing.

4. Pull out lower air cleaner housing with air flow sensor and pull off plugs.

Press bar in direction of arrow while pulling off plugs.

Installing

1. Install fuel cooler.

a) Check that seals on refrigerant line connections are not damaged, replacing if necessary.

b) First connect left refrigerant line on fuel cooler. Do not tighten coupling fully at this point.

c) Connect and tighten both fuel lines on fuel cooler, while counterholding.

d) Connect right refrigerant line.

e) Tighten both refrigerant line couplings on fuel cooler, holding on hexagon each time and being careful that fuel cooler is not turned.

f) Install and bolt bracket for fuel cooler.

2. Mount air flow sensor together with lower air cleaner housing, connecting wires on air flow sensor and air cleaner.

Tighten lower air cleaner housing mounting screws.

Install filter element and upper air cleaner housing, connecting hose from blowoff switching valve on upper air cleaner housing.

3. Connect battery.

4. Start engine and run approx. 15 seconds while checking fuel line connections on fuel cooler for leaks.

Tighten fuel line connections if necessary.

5. Flush, discharge and charge air conditioner as described in Group 87 of Repair Manual 928.

SPECIFICATIONS FOR TESTING AND ADJUSTING LH-JETRONIC TYPE 928 S 85 MODEL ONWARD (32-VALVE ENGINES) ENGINE TYPE M28. 43/44/45/46

Test

Specification

Remarks

Electric fuel pump delivery rate

min. 1350 cm3/ 30 s

Fuel pressure (engine off) fuel pump bridged

2.3 2.7 bar

Overpressure at idle speed

approx. 2 bar

Leak test minimum pressure after 20 minutes

1 bar

Idle speed in rpm 1/min

CO-content %

680 + 20 0.6 % + 0.2 %

Specifications for Testing 24 - 201 and Adjusting

EQUIPMENT CHART LH - JETRONIC - TYPE 928 S

85 MODELS ONWARD (32-VALVE ENGINES)

ENGINE TYPE M 28.

43/44/45/46

Electric

Fuel filter

Fuel pres

Fuel

fuel pump

sure damper

pressure

(intake)

regulator

928.608.104.01

928.110.253.00

928.110.202.00

928.110.198.01

Bosch No.

Purolator No.

Bosch No.

Bosch No.

0580.464.017

506.883.901.5

0280.161.008

0280.160.215

Hot wire

NTC

Throttle

Idle

air volume

Temperature

switch

adjuster

meter

sensor II

(dual function)

928.606.141.00

928.606.126.00

944.606.113.01

928.606.161.00

Bosch No.

Bosch No.

Bosch No.

Bosch No.

0280.214.001

0280.130.032

0280.120.308

0280.140.509

Electric

LH-Jetronic

LH-Jetronic

injection

control unit

control unit

valves

85 models

86 models

M28. 43/44

M28. 43/44/45/46

928.606.120.00

928.618.123.03

928.618.123.04

Bosch No.

Bosch No.

Bosch No.

0280.150.706

0280.002.50

0280.002.503

ADJUSTING IDLE (32 VALVE ENGINE) Tools

No.

Description

Special Tool

Remarks

1

Oil temperature tester with test probe

9122 + 9122/1

or US 8025

2

Adapter

US 8040

3

Exhaust probe

US 4492

4

Screwdriver

9230

5

7 mm hexagon key

e.g. Hazet 428 - 7

6

Lead

Made locally

It is recommended to use the test connection in area of air cleaner housing, if there is suspicion of erratic engine running or when troubleshooting.

CO testing pipe for cylinders 1 - 4 is on righthand side, or lefthand side for cylinders 5 - 8.

2. Disconnect oxygen sensor plug and connect CO tester according to supplier's instructions.

3.Install Special Tool US 4492 on CO testing pipe.

4. Check CO. If CO level deviates from specified value, correct the adjustment on air volume sensor. Use Special Tool 9230.

ADJUSTING IDLE (32 VALVE ENGINE)

Note

Engine in perfect mechanical condition. Electric equipment switched off during adjustments. Adjustments made as quickly as possible to prevent heating up the intake ports and consequently causing wrong CO values.

1. Run engine to operating temperature (oil temperature 80 to 90° C). Use Special Tools 9122 + 9122/1 to check oil temperature: 15 to 30° C.

2. Disconnect oxygen sensor plug and connect CO tester according to supplier's instructions.

3.Install Special Tool US 4492 on CO testing pipe.

It is recommended to use the test connection in area of air cleaner housing, if there is suspicion of erratic engine running or when troubleshooting.

CO testing pipe for cylinders 1 - 4 is on righthand side, or lefthand side for cylinders 5 - 8.

CO adjusting value: 0.6 + 0.2 % Turned clockwise - richer mixture

Turned anticlockwise - leaner mixture

If the CO level has to be corrected on the air volume sensor, remove plug in bore affording access to the idle speed CO adjusting screw after removal of the air volume sensor.

CO adjusting value: 0.6 + 0.2 % Turned clockwise - richer mixture

Turned anticlockwise - leaner mixture

If the CO level has to be corrected on the air volume sensor, remove plug in bore affording access to the idle speed CO adjusting screw after removal of the air volume sensor.

5. Connect oxygen sensor plug and insert plug in CO testing pipe after finishing adjustments.

6. Connect separate tachometer to supplier's instructions.

Idle speed adjusting value: 680 + 20 rpm.

7. Check and adjust idle speed.

This requires stopping the idle speed charging control.

a) Connect test jacks B and C with a piece of locally made wire. This stops idle speed charging control.

b) Check and adjust speed with, for example, VAG Tester 1367.

8. Turn control screw (bypass) on throttle housing with a standard screwdriver, e.g. Hazet 428 - 7, until the specified speed of 680 + 20 rpm.

Porsche Supplier Hazet

9. Restore idle speed charging control after finishing adjustments (remove locally made wire on test jacks).

10. Recheck adjusted values.

CORRECTING CO ADJUSTMENT ON AIR VOLUME SENSOR (32 VALVE ENGINE)

Note

If CO level deviates from the specified value, remove plug in bore affording access to the CO adjusting screw after removal of the air sensor.

Removing

1. Remove air sensor.

2. Drill hole in plug with a 2 mm dia. drill (up to stop on steel insert).

3. Pull out plug with a lefthand spiral drill (size no. 2).

3. Install a new plug in bore affording access to CO adjusting screw after finishing adjustments. Press in plug flush.

Note

Drilled plugs must never be reused.

Installing 1. Install air sensor.

2. Adjust CO and engine idle speed. Turn CO adjusting screw accordingly with Special Tool 9230.

Turned clockwise - richer mixture Turned anticlockwise - leaner mixture

Porsche 928 M28

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FUEL PATH - LH-JETRONIC 928 S 85 MODELS ONWARD (32-VALVE ENGINES) ENGINE TYPE M28. 43/44/45/46

928 Fuel Line Diagram

a

- connection, USA

1 -

fuel pump

9 -

fuel

b

- connection, California

2 -

fuel filter

cooler

3/3a -

pressure damper

10 -

underpressure

A

- from fuel tank

4 -

left-hand

distributor

B

- to fuel tank

injection line

11 -

throttle valve

C

- vent to oil filter

5 -

righ-hand

body

neck

injection line

12 -

Blow-off valve

D

- from activated charcoal

6 -

test point

13 -

Thermo switch

cannister

E

- to automatic transmission

7 -

injectors

14 -

air-bleed

F

- to ECU

8 -

pressure

valve

regulator

Porsche 928 Throttle Body Connection

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