AUDI A8 1998 D2 / 1.G AHA Engine Motronic Ignition System Owner's Manual

-
Press button.
- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

- Check readiness code page 01
-70
.

If Diagnostic Trouble Code (DTC) memory has
been erased, or ECM has been disconnected,
generate new readiness code page 01
-73
.
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If displayed values are NOT OK:

- Press -C- button.

- Press buttons -0-, -1- and -5- to input display
group number 15 (015), and press -Q- button to
confirm input. Read Measuring Value Block 15 1 2 3 4

Indicated on display (1-4 display groups) - Compare displayed values with specified values for misfire recognition
(display fields 1-4):

Display groups

1 2 3 4
Display group 15: Misfire recognition
Display xxx xxx xxx activated
deact
Indicates Misfire harmful to
emissions, Cyl. 1 Misfire harmful to
emissions, Cyl. 2 Misfire harmful to
emissions, Cyl. 3 Misfire recognition
status
Range 500 500 500 ---
Specified
value 0 - 5 0 - 5 0 - 5 activated

If displayed values are NOT OK page 28
-20
, Evaluation of display groups 15 and 16
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If displayed values are OK:

- Press -C- button.

- Press buttons -0-, -1- and -6- to input display
group number 16 (016), and press -Q- button to
confirm input. Read Measuring Value Block 16 1 2 3 4

Indicated on display (1-4 display groups) - Compare displayed values with specified values for misfire recognition
(display fields 1 and 4):

Display groups

1 2 3 4
Display group 16: Misfire recognition
Display xxx xxx xxx activated
deact
Indicates Misfire harmful to
emissions, Cyl. 4 Misfire harmful to
emissions, Cyl. 5 Misfire harmful to
emissions, Cyl. 6 Misfire recognition
status
Range 500 500 500 ---
Specified
value 0 - 5 0 - 5 0 - 5 activated

If displayed values are NOT OK page 28
-20
, Evaluation of display groups 15 and 16
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Evaluation of display groups 15 and 16 Display groups: 15
and 16


Display fields: 2 and
3
Possible malfunction cause
Corrective action
greater than 5

Ignition coil faulty
Spark plug connector faulty
Spark plug faulty
Power output stage for
ignition coil faulty - Check ignition coils -N-, -N128- and -N158- with power output
stage -N122 page 28
-21



Fuel injector faulty
Not enough fuel- Check fuel injectors page 24
-102
- Check fuel in tank
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28-21

Ignition coils and power output stage,
checking


Notes:

The ignition coils and power output stage are
one component.
Measuring the primary resistance of the ignition
coils is not possible.
Measure secondary resistance first with ignition
wires connected to the ignition coil via the spark
plug connector of the respective cylinder (with
this method the interference resistances of the
ignition cables are also measured).
Component locations page 24
-1

Required special tools and test equipment

Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit

Test conditions
No fuel injector malfunction stored in DTC
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memory
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Checking

- Check DTC memory page 01
-16
.

There must be no malfunctions stored

- If DTC memory is not clear (malfunctions
recognized):

- Make necessary repairs and erase DTC
memory.

- Stop engine and start engine again.

- Road test.

- Check and erase DTC memory again.

- By briefly disconnecting fuel injector connectors
with engine running, check which cylinder is
misfiring, or not firing at all.
A misfiring cylinder can also be isolated by
examining the spark plugs (for a carbon-fouled
plug).

-
Interchange spark plug with one from cylinder
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that is OK.
If a different cylinder now misfires:

- Replace faulty spark plug.
If the original cylinder misfires:

- Check ignition coil page 28
-23
.
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Checking ignition coils -N-, -N128- and -N158-


- Disconnect 5-pin connector from ignition coil
assembly.

- Remove ignition wires from spark plugs.

If resistance is NOT OK: - Using multimeter and adapters from VAG1594 connector test kit,
measure resistance between both spark plug connectors of respective
ignition circuit (across coil).

Specification: approx. 18-25 k .- Remove ignition wires from ignition coils and measure resistance
between ends of respective ignition wires.

Specification: approx. 4.0-6.0 k
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28-24


If resistance values are not as specified:
If resistance values are OK: - Using multimeter and adapters from VAG1594 connector test kit,
measure resistance across both ignition wire connectors of respective
ignition coil.

Specification: 8.0-14.0 k - Replace coils.
- Check signal for power output stage page 28
-25
.
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