AUDI A8 1999 D2 / 1.G ATQ Engine Ignition System Checking Workshop Manual

28-1


Ignition system, checking

General notes on ignition system


The battery should only be disconnected and
reconnected when the ignition is turned off,
since otherwise the Engine Control Module
(ECM) can be damaged.
The Engine Control Module (ECM) is equipped
with an On Board Diagnostic (OBD)
For the electric components to work properly, a
voltage of at least 12.7 V is required.
It is possible that the control module will
recognize a malfunction and store a DTC during
some tests. After completing all tests and
repairs, DTC memory should therefore be
checked and erased if necessary.
If the engine only starts briefly and then turns
off again after troubleshooting, repair or
checking of the components, it may be that the
immobilizer is blocking the Engine Control
Module (ECM). DTC memory must then be
checked and if necessary, control module must
be adapted.
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Safety precautions

To reduce the risk of personal injury and/or
damage to the fuel injection and ignition system,
always observe the following:

Do not touch or pull off ignition wires when
engine is running or turning at starting RPM.
Always switch ignition off before disconnecting
or reconnecting wires for the injection and
ignition system, including high voltage wiring
and test leads.
If engine is to be cranked at starting RPM
without starting (e.g. for compression testing),
disconnect connector from ignition coils and
from fuel injectors.
It is possible that the control module will
recognize a malfunction and store a DTC during
some tests. After completing all tests and
repairs, DTC memory should therefore be
checked and erased if necessary. Readiness
code must be generated after DTC memory is
erased Page 01
-82
.

Always switch ignition off before cleaning
engine.
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The battery should only be disconnected and
reconnected when the ignition is turned off,
since otherwise the Engine Control Module
(ECM) can be damaged.
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Technical data, ignition

Engine identification
ATQ (2.8 L / 5V/ 147 kW-engine)
Idle speed
Engine speed cannot be adjusted, it is regulated by idle stabilization 720 to 820 RPM (front wheel drive)
630 to 730 RPM (all wheel drive)
Engine speed (RPM) limitation
via fuel injector shut-off
about 6800 RPM
Ignition timing is determined in the control module
It is not possible to adjust the ignition timing
Ignition system Dual-spark ignition system with three ignition coils
Spark plugs Tightening torque 30 Nm.
Firing sequence 1-4-3-6-2-5
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Ignition system components, removing
and installing

1 -
Spark plug, 30 Nm
Remove and install with 3122 B
2 -
Spark plug connectors with ignition wires
3 -
Spacer sleeve
4 -
Rubber grommet
5 -
10 Nm
6 -
Ignition coils (-N-, -N128-, -N158-) With power output stage -N122-With marking for ignition wires, do not
interchange
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28-5


7 -
5-pin harness connector
Black
8 -
3-pin harness connector Terminals are gold-plated
9 -
20 Nm Tightening torque affects function of Knock
Sensor (KS)
10 -
Knock Sensor (KS) 2 -G66- Bank 2Terminals of sensor and connector are
gold-plated
11 -
Knock Sensor (KS) 1 -G61- Bank 1Terminals of sensor and connector are
gold-plated
12 -
10 Nm
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13 -
Camshaft Position (CMP) sensor 2 -G40-
Bank 2
14 -
25 Nm
15 -
Washer Conical
16 -
Face plate for Camshaft Position (CMP) sensornote position when installing
17 -
3-pin harness connector Blackfor Camshaft Position (CMP) sensor -G40-
or -G163-
18 -
Camshaft Position (CMP) sensor 2 -G163- Bank 1
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28-7


Ignition coils, checking

Special Tools and Equipment

VAG1526A
VAG1527B
VAG1594A
VAG1598/31
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28-8
Component location Overview of Component
Locations, page Page 24
-5

Notes:

Ignition coils and power output stage are a
common part.
Primary resistance of ignition coils cannot be
measured.
Secondary resistance must first be measured
with the ignition wires connected to the ignition
coils via the spark plug connectors of the
corresponding cylinder (This measurement will
include measurement of the shielded
resistances of the ignition wires).

- Disconnect 5-pin connector from ignition coils.

Check ignition coils (-N-, -N128- and -N158-)

- Pull the ignition wires from the spark plugs.

- In order to perform a resistance measurement, connect multimeter
between both spark plug connectors of the respective ignition circuit to
be checked.

Specification: each 16 to 27 k
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- If the specified values are not reached, disconnect ignition wires from
ignition coils and perform a separate resistance measurement at the
ignition wires and at the ignition coils.
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