AUDI A3 1998 8L / 1.G ATW Engine Ignition System Workshop Manual

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Ignition system, checking

General notes on ignition system


Note:

The battery should only be disconnected and
reconnected when the ignition is turned off,
since otherwise the Engine Control Module
(ECM) can be damaged.
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 disconnect 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
-73
.

Always switch ignition off before cleaning
engine.
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Technical data

Engine identification
ATW (1.8 L / 5V/ 110 kW engine)
Idle speed
Engine speed cannot be adjusted, it is
regulated by idle stabilization Front Wheel Drive (FWD): 740 to 860 RPM
All-Wheel Drive Vehicles: 800 to 920 RPM
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 Single coil ignition system with 4 ignition coils (power output stages integrated)
that are connected directly to spark plugs via the ignition cables.
Spark plugs Tightening torque 30 Nm.
Firing sequence 1-3-4-2
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Ignition coils with power output stages,
checking

Special tools and equipment

VAG1526A
VAG1527B
VAG1594A
VAG1598/31
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Test sequence

Note:
The ignition coil and power output stage are
combined in one complete component.

Recognize a non-functional or misfiring cylinder as follows:
If misfires were recognized:
If no misfires were recognized:
or
If faulty cylinder is recognized: - Remove engine cover (arrows).
- Check misfire recognition Page 28
-51
.
- Continue with test at indicated cylinder "If faulty cylinder is
recognized". - Disconnect connectors from fuel injectors in sequence with engine
running and observe engine operation.
- Compare spark plugs from all cylinders to each other. Check
electrodes for carbon fouling..
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- Switch spark plug from faulty cylinder with one from another cylinder.
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If malfunction follows the spark plug:

- Replace spark plug.
If malfunction remains at original cylinder:

- Switch ignition coil from faulty cylinder with one
from another cylinder.
If malfunction follows the ignition coil:

- Replace ignition coil.

Check Ground (GND) connection

- Disconnect 4-pin harness connector -1- at ignition coil -2-.
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If LED does not light up:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If LED lights up:
Checking voltage supply
Test requirement:
Electrical Wiring Diagrams, Troubleshooting & Component Locations - Connect VAG1527B voltage tester as follows:Harness connector
Terminal
Measure to
2 B+
4 B+

LED must light up.
- Check wire connections.
- Check voltage supply
Fuses for engine electronics OK
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If specified value is obtained:
If specified value is not obtained: - Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
1 Engine Ground (GND)
- Switch ignition on.

Specification: approx. battery voltage
- Check activation of power output stages Page 28
-10
.

- Pull off rubber seal of plenum chamber cover in direction of arrow.
- Remove cover -1- toward front.
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- Remove Heater Core E-box cover (arrows).

- Disconnect voltage supply relay -3-.
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