1997 AUDI A8 AEB Engine Motronic MFI And Ignition System

24-89
If LED does not flicker:

- Switch ignition off.

- Connect VAG 1598/22 test box to ECM harness
connector Page 01
-56
.

- Check wiring for open circuits between ECM/test
box and fuel injector harness connectors:


Cyl. 1 fuel injector terminal 2 to ECM/test
box socket 73

Cyl. 2 fuel injector terminal 2 to ECM/test
box socket 80

Cyl. 3 fuel injector terminal 2 to ECM/test
box socket 58

Cyl. 4 fuel injector terminal 2 to ECM/test
box socket 65

Specified value: max. 1.5

- Check wiring for open circuit between fuel
injector connector terminal 1 and relay panel,
according to wiring diagram.
Pa
ge 121 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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pair&id=AUDI.B5.FU02.24.1

Specified value: max. 15
- Check wiring for short circuits between wires
and connector terminals.


Specified value:
Pa
ge 122 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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e=re
pair&id=AUDI.B5.FU02.24.1

24-90

Fuel injector resistance, checking


Note:
With engine at operating temperature, resistance increases by approx. 4-
6
If resistance is NOT OK: - Check resistance of individual fuel injectors.

Specified value: 11-13 - Replace affected fuel injector.
Pa
ge 123 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

24-91

Fuel injectors, checking for leakage


WARNING!

The fuel system is under pressure! Before
loosening hoses or opening the test
connection, cover the connection with a rag.
Only then, open carefully to slowly release
pressure.

Required special tools and test equipment

VW 1594 connector test kit
VAG 1630 digital potentiometer
VAG 1602 fuel analyzer

Checking

- Disconnect harness connector for Camshaft
Position (CMP) sensor -G40-.

- Disconnect vacuum hose from fuel pressure
regulator.

- Remove fuel rail together with fuel injectors.

Pa
ge 124 of 135 Motronic Multi
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jection
(MFI
) and i
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

- Insert fuel injectors in VAG 1602 fuel analyzer.
Pa
ge 125 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

24-92


Note:
When reinstalling the fuel injectors be careful not to damage the O-rings. - Disconnect harness connector for Engine Coolant Temperature (ECT)
sensor -G62-.
-
Adjust VAG 1630 digital potentiometer to 15 k setting.- Connect to ECT sensor harness connector terminals 1 and 3, using
adapter cables from VW 1594 connector test kit.
- With the aid of a helper, briefly crank starter.
Fuel injectors must spray according to the firing order.
- Switch ignition off, and check for leaks at fuel injectors.
Fuel injectors may not drip more than 2 drops per minute.
Pa
ge 126 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

24-93

Fuel pressure regulator and residual
pressure, checking

The fuel pressure regulator controls the fuel
pressure depending on intake manifold
pressure.

Required special tools and test equipment

Pressure tester VAG 1318
Adapter 1318/11
Adapter 1318/12
Adapter 1318/13

Test requirements
Fuel pump delivery rate must be OK;
checking:

Repair Manual, Fuel Supply System, Repair
Group 20.


Checking
Pa
ge 127 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1

WARNING!

The fuel system is under pressure! Before
loosening hoses or opening the test
connection, cover the connection with a rag.
Only then, open carefully to slowly release
pressure.
Pa
ge 128 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
ystem
11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU02.24.1