2000 AUDI A8 AEB Engine Motronic MFI And Ignition System

24-7

Rules of cleanliness


CAUTION!

Whenever carrying out work on the fuel
supply and fuel injection systems, carefully
observe the following five rules of
cleanliness.
1. Thoroughly clean fuel system line and hose
connections and the surrounding area before
disconnecting.
2. Place removed components on a clean
surface and cover. Use plastic sheeting or paper.
Do not use fluffy rags that could leave lint!
3. Carefully cover over or seal any components
that have been opened if repairs are not carried
out immediately.
4. Install only clean parts:

Do not remove replacement parts from the
packaging until immediately before they are to
be installed.
Do not use parts that have been stored without
packaging (e.g. in toolboxes, etc.).
5. When the fuel system is opened:
Pa
ge 9 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

Avoid working with compressed air whenever
possible.
Avoid moving the vehicle if possible.
Pa
ge 10 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

24-8
Technical data

Engine code
AEB

Engine idle speed:
not adjustable, maintained by Idle Air Control (IAC) 820-900 RPM
Engine speed (RPM) upper limit:
actuated by switching off fuel injectors approx. 6500 RPM
Fuel system pressure at idle Vacuum hose for pressure regulator connected: approx. 3.5 bar
(50 psi)

Vacuum hose for pressure regulator disconnected: approx. 4.0 bar
(58 psi)

Residual fuel pressure after 10 minutes at least 2.5 bar
Fuel injectors Spray pattern: approx. the same for all fuel injectors

Resistance
1)
:
11-13 ohm
1) Engine at room temperature; with the engine at normal operating temperature the resistance increases by approx. 4-6
ohms.
Pa
ge 11 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

24-9

Fuel injection system, servicing

Servicing ignition system:

Repair Group 28

Notes:

Fuel hoses in the engine compartment must be
secured with spring-type clamps. Screw-type
clamps or equivalent must not be used.
The Engine Control Module (ECM) has On
Board Diagnostic (OBD) capability, and is
equipped with Diagnostic Trouble Code (DTC)
memory. Before repairing or adjusting any
components or systems, first check DTC
memory. Also check all vacuum connections for
leaks ("false air").
For proper operation of electrical and electronic
components, a Battery Positive Voltage (B+)
supply of at least 11.5 volts is required.
Do not use any gasket sealers or other
automotive chemical compounds that contain
silicone. Traces of silicone drawn into the
engine pass unburned into the exhaust and can
damage the oxygen sensors.
Pa
ge 12 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

Do not use any electrical contact sprays or
equivalent near oxygen sensor connections.
Proper oxygen sensor function requires
reference to outside air via the cable. If any
contact spray reaches the oxygen sensor, it can
cause damage or improper function.
During some tests, malfunctions are recognized
by the ECM and stored in DTC memory. For
this reason, always check DTC memory after all
tests and repairs, and erase DTC memory as
necessary.
Pa
ge 13 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

24-10
Safety precautions Page 24
-5
Rules of cleanliness Page 24
-7
Technical data Page 24
-8
Pa
ge 14 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

24-11

Idle speed, checking


Notes:

Idle speed, ignition timing and CO-content
cannot be adjusted.
Idle speed is maintained by the Throttle valve
control module.
CO-content is maintained and adjusted by
Oxygen Sensor (O2S) control. Malfunctions in
O2S control are recognized by On Board
Diagnostic (OBD) and stored in DTC memory.

Required special tools and test equipment
VAG 1551 Scan Tool (ST) with VAG 1551/3
adapter cable

Test conditions
No malfunctions stored in DTC memory
Page 01
-15


Engine Coolant Temperature (ECT) at least
85 C (185 F)

All electrical consumers switched off
Pa
ge 15 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

(radiator coolant fan must not run during
test)
A/C switched off
Exhaust system free of leaks
Automatic transmission selector lever in "P"
or "N" position
Pa
ge 16 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