1998 AUDI A4 fuel pressure

28-34

Knock sensor control limit, checking

If the malfunction message "Knock control
regulation reached" is recorded in the DTC
memory the following tests must be carried out.
See also measuring value blocks 20, 21, 22, 23
and 24 Page 28
-35


Possible cause of malfunction
Corrective action
Malfunction
message relating to all cylinders
Poor fuel quality- Change to higher quality fuel (see Owner's
Manual)
or
malfunction
message relating to all cylinders in
one bank Incorrect tightening torque on
knock sensor - Loosen knock sensor, then tighten to 20
Nm (15 ft lb)
Knock sensor faulty- Check knock sensor Page 28
-41
.

Corrosion on connector
Loose components on engine- Secure loose components
Malfunction
message relating to one cylinder Mechanical engine damage- Check compression pressure
Loose components on engine- Secure loose components
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28-40
Evaluation display groups 20/21/22/23/24, - Ignition timing angle retard Indicated on display
Malfunction cause
Corrective action
All cylinders greater
than 12 KW
Knock sensor faulty- Check knock sensor Page 28
-41
.


Corroded connection

Knock sensor incorrect
tightening torque - Loosen and tighten knock sensor with 20 Nm (15 ft lb)

Components on engine
loose - Tighten components

Low fuel grade- Change fuel grade
One cylinder deviates
clearly from others Corroded connection- Check knock sensor Page 28
-41
.


Engine damage
Repair Manual, 2.7 Liter V6 5V BiTurbo Engine Mechanical, Engine
Code(s): APB, Repair Group 15, Cylinder head removing, check compression pressure
- Check compression pressure:


Components on engine
loose - Tighten components
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28-54
Evaluation display group 014, display field 3 Display field:
3
Possible cause
Corrective action
greater 15

Spark plug faulty
Spark plug connector faulty
Ignition coil or power output stage faulty- Check spark plug and ignition cable with
connector
- Check ignition coil Page 28
-5 .
- Check power output stages Page 28
-11


Fuel injector faulty
Check compression of one or more cylinder
weak - Check fuel injectors Page 24
-39
- Check compression pressure
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28-57
Evaluation display groups 015 and 016 Display field: 1,2 and 3 from measuring
value block 15 and 16
Possible cause
Corrective action
greater 15
Spark plug faultySpark plug connector faulty Ignition coil or power output stage
faulty - Check spark plug and ignition
cable with connector
- Check ignition coil Page 28
-5 .
- Check power output stages
Page 28
-11


Fuel injector faultyCheck compression of one or
more cylinder weak - Check fuel injectors Page 24
-39
- Check compression pressure
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