2000 AUDI A8 AEB Engine Motronic MFI And Ignition System

24-94

- Open fuel filler cap briefly (release pressure).

- Cover the fuel supply line connection (arrow) to protect against fuel
spray.
- Slowly open connection and catch leaking fuel.

Note:
The valve on the pressure tester must be open (lever pointing in direction
of flow). - Connect pressure tester VAG 1318 to fuel rail using adapters VAG
1318/11, VAG 1318/12 and VAG 1318/13.
- Start engine and let run at idle.
- Measure fuel pressure.
Specified value: approx. 3.5 bar (50 psi)
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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.
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If residual pressure still drops below 2.5 bar (36
psi), possible malfunctions are:

Leaking connection between pressure tester
and fuel line
Leaking connection between fuel supply line
and fuel rail
Faulty check valve in fuel pump; removing and
installing:

Repair Manual, Fuel Supply System, Repair
Group 20

If residual pressure no longer drops below 2.5
bar (36 psi), the possible malfunctions are:

Leaking fuel pressure tester connections after
shut-off valve.
Faulty fuel pressure regulator
Leaking fuel injectors

Note:
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When disconnecting the pressure tester, close
the shut-off valve, disconnect adapter VAG
1328/12, then catch excess fuel in a container by
opening the shut-off valve.
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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
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Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08, and press -Q- button to confirm input.
Read Measuring Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -0- and -1- to input display group number 1, and
press -Q- button to confirm input.
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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