check engine AUDI A8 1999 D2 / 1.G AEB Engine Motronic MFI And Ignition System

24-87

Fuel injector actuation, checking

Triggering fuel injectors via output Diagnostic
Test Mode (DTM) Page 01
-42


Required special tools and test equipment

VAG 1598/22 test box
Multimeter US 1119 (Fluke 83 or equivalent)
VAG 1527B LED voltage tester
VW 1594 connector test kit
Wiring diagram

Test requirements
Fuse for fuel injectors OK
Engine speed (RPM) sensor OK
Fuel pump relay OK
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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.
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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
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24-95


If residual pressure drops below 2.5 bar (36 psi): - Disconnect vacuum hose (arrow) for fuel pressure regulator.
Fuel pressure must increase to approximately 4.0 bar (58 psi)
- Reconnect vacuum hose.
- Switch ignition off.
- Check for residual fuel pressure by monitoring decrease in pressure on
gauge. Specified value:
After 10 minutes: at least 2.5 bar (36 psi)
- Start engine and let run at idle.
- After pressure has built up, at the same time:
- Switch ignition off.
- Close valve on pressure tester VAG 1318-lever in OFF position
(arrow).
- Monitor decrease in pressure on gauge.
Pa
ge 130 of 135 Motronic Multi
port Fuel In
jection
(MFI
) and i
gnition s
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11/19/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
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yp
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24-97

Intake air system, checking for leaks
(false air)


Required special tools and test equipment

VAG 1551 or VAG 1552 Scan Tool (ST) with
VAG 1551/3 adapter cable
Engine leak detector spray G 001 800 A1

Notes:
If there are leaks, intake manifold vacuum will
draw in the leak detector spray with outside air.
The spray reduces the ability of the fuel/air
mixture to ignite, which causes a drop in engine
speed and a significant increase in CO-content.
Observe the safety precautions listed on the
container.

Checking

- Connect VAG 1551 or VAG 1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) Page 01
-7 .
Rapid data transfer
HELP

Indicated on display
Pa
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(MFI
) and i
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24-98

If engine speed drops, or the value displayed for oxygen sensor control changes:
Read Measuring Value Block 1 1 2 3 4

Indicated on display (1-4 = display fields)
- Monitor oxygen sensor control in display field 3.

Display fields

1 2 3 4
Display group 1: Idle test
Display xxxx RPM
xxx.x C
xx.x% xxxxxx
Indicates Engine speed
(in 40 RPM
steps) Engine
temperature Oxygen sensor control Adjustment
conditions
Range 0-6800 RPM --- -25.0 to 25.0 % ---
Specified
value 760-960 RPM --- In the range of -10.0 to 10.0% the value must
fluctuate by at least 2% ---
- Systematically spray parts of intake air system with engine leak detector spray.
- Check for leaks in area of intake air system most recently sprayed, and eliminate leaks.
Pa
ge 135 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