fuel AUDI A8 1998 D2 / 1.G ATQ Engine Motronic Injection System Servicing Owner's Guide

24-48

- Bridge terminals 1 and 65 at test box using wires
from VAG1594A adapter test kit.


Fuel Pump (FP) must run.

- Operate VAG1348/3A remote control for 30
seconds.

- After all three fuel injectors of one cylinder row
have been activated, place measuring glasses
on an even surface.

Specified value for each fuel injector: 90 to
125 ml.

- If measured value of one or more fuel injectors
is outside of specified range, switch Fuel Pump
(FP) off (disconnect cable bridge) and replace
faulty fuel injector Page 24
-43
.

- Repeat test at fuel injectors of second cylinder
row.

- If the measured values of all fuel injectors are
outside the specified range, check fuel pressure
Page 24
-30
.

Note:
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Also check spray pattern when checking injection
quantity. Spray pattern must be the same for all
injectors

- Install fuel injectors together with fuel distributor
Page 24
-44
.
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24-49


Fuel Pump (FP) relay -J17- and activation,
checking

Special Tools and Equipment

VAG1526A
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3B
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24-50
Voltage is supplied to the Fuel Pump (FP) and
several components of the injection system via
the Fuel Pump (FP) relay -J17-.
Engine must be turning for Fuel Pump (FP) relay
-J17- to close. This means that the relay does
not receive Ground (GND) (via ECM) until the
ECM recognizes RPM signals.

Note:

Fuel Pump (FP) relay is located at position 4 of central electrics in driver's
footwell, left.
Test requirement:
Battery voltage at least 12.7 V
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24-51

Function test of Fuel Pump (FP) relay

- Remove driver-side storage compartment.

Repair Manual, Body
-Interior, Repair Group
68; Instrument Panel; Removing Driver
-Side
Storage Compartment


- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Ignition must remain switched on for this.

- Initiate output Diagnostic Test Mode Page 01
-
56
and activate Evaporative Emission (EVAP)
canister purge regulator valve -N80-.

A - If relay does not trigger:
Fuel Pump (FP) relay (at position 4 of central electrics in driver's
footwell, left) must trigger and Fuel Pump (FP) must run.
- Check voltage supply of Fuel Pump (FP) relay Page 24
-52
.
- Checking activation of Fuel Pump (FP) relay Page 24
-52
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24-52
B - If relay triggers, but Fuel Pump (FP) does not
run:

- Check voltage supply for Fuel Pump (FP) and
components (via Fuel Pump -FP- relay) Page
24
-54
.

Check voltage supply of Fuel Pump (FP)
relay

- Remove Fuel Pump (FP) relay.

If specified value is not obtained:
Checking activation of Fuel Pump (FP) relay - Connect multimeter to terminal 17 of relay socket and Ground (GND)
for voltage measurement.

Specification: approx. battery voltage
- Replace central electrics.
- Switch ignition off.
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM Page 24
-17
.
- Bridge terminals 1 and 65 at test box using wires from VAG1594A
adapter test kit.
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24-53


If relay triggers now, but didn't during output DTM:
If relay does not trigger:
Fuel Pump (FP) relay (at position 4 of central electrics in driver's
footwell, left) must trigger.
- Replace Engine Control Module (ECM) Page 24
-21
.
- Remove cable bridge.
- Remove Fuel Pump (FP) relay.

If specified value is not obtained:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
binder - Connect multimeter to terminal 19 of relay socket and Ground (GND)
for voltage measurement.

Specification: approx. battery voltage
- Check wire connections.
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24-54
If specified value is obtained:

If no malfunctions are detected:
Check voltage supply for Fuel Pump (FP) and components - Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+:
Central electric
in driver-side footwell, left, position 4
Terminal
VAG1598/31 test box


Socket
16 65
- Repair open circuit or short circuit if necessary.
- Replace Fuel Pump (FP) relay -J17-.
- Re-connect Engine Control Module (ECM).

- Remove fuses S228, S229, and S234 (positions 28, 29, and S234)
from fuse holder.
- Initiate output Diagnostic Test Mode Page 01
-56
and activate
Evaporative Emission (EVAP) canister purge regulator valve -N80-.
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24-55

- Connect multimeter for voltage measurement to
Ground (GND) and to one terminal of the
following fuses in the fuse holder.

Fuse
Specified value at one of the
terminals
S228 approx. battery voltage
S229 approx. battery voltage
S234 approx. battery voltage
If specified values are not obtained:

- Repeat test at another terminal of fuse socket.
If specified values are not obtained again:

- Check wire connections.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder If no malfunctions are detected:

- Replace Fuel Pump (FP) relay -J17-.

- Re-insert the fuses.
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24-59
If specified values are obtained:

-
Press button.Rapid data transfer
HELP
Select function XX

Indicated on display (function selection):
Evaluation display group 002
Display field: 3
Possible cause
Corrective action
less than 1.0
ms
Smaller values are only possible when driving in
deceleration mode
larger than 4.0
ms Engine under load due to power accessories.- Reduce load (A/C system/power
steering/generator)

Poor idle (does not run on all cylinders)- Check spark plugs.
- Check fuel injectors Page 24
-36


Throttle valve control module - J338- faulty- Check throttle valve control module Page
24
-141

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