1995 AUDI A4 fuel

24-1


Motronic Multiport Fuel
Injection (MFI) system,
servicing

Safety precautions


Observe following precautions if test and
measuring instruments are required during a
road test:

WARNING!

During a road test in an airbag equipped
vehicle, test equipment must always be
fastened to and operated from the rear seat
by a second technician.
When driving or riding in an airbag equipped
vehicle, NEVER hold the scan tool or other
test equipment in your hands or lap while in
motion. Objects between you and and the
airbag increase the risk of injury in an
accident.

To prevent injuries to persons and/or damage
to the fuel injection and ignition system, the
following must be noted:
Always switch off the ignition before
connecting or disconnecting injection or
ignition system wiring or tester cables.
Pa
ge 1 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

Fire hazard! Do not smoke, work near
heaters or open flame, or have anything
nearby that could ignite fuel. The fuel system
is pressurized. Before loosening hose
connections or opening the test connection
(to measure fuel pressure), place a cloth
around the connection. Then release
pressure by carefully opening the
connection.
Pa
ge 2 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

24-2

CAUTION!

To operate the engine at starter speed
without actually starting it (for example, in
order to test compression), unplug the
connectors from the output stages for the
ignition coils and also the connectors on the
injectors.
During some of the tests the control module
may identify and record malfunctions. The
DTC memory should therefore be checked
and (if necessary) erased after completing
the tests and any repair work that may be
required. After erasing DTC memory
generate new readiness code Page 01
-
105
.

Always switch off the ignition before
cleaning the engine.
Always switch off the ignition before
connecting or disconnecting the battery,
otherwise the engine control module may be
damaged.
Be sure of proper radio code (for vehicles
equipped with coded anti-theft radio)

Be sure the battery negative (-) cable is
Pa
ge 3 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

disconnected, when:

Working on the electrical system.

When connecting and disconnecting
electrical test equipment (LED voltage tester,
multimeter, etc.):
Be sure the ignition is switched OFF.
Use correct adapters from the VAG1594
connector test kit.
Pa
ge 4 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

24-3

Rules for cleanliness


When working on the fuel supply/injection
system, pay careful attention to the 6
following rules for cleanliness:

Thoroughly clean all connections and the
adjacent areas before disconnecting.
Place parts that have been removed on a clean
surface and cover them over. Do not use fluffy
cloths.
Carefully cover or seal opened components if
the repair cannot be completed immediately.
Only install clean components: Only unpack
replacement parts immediately prior to
installation. Do not use parts that have been
stored loose (e.g. in tool boxes etc.).
When the fuel system is open: Do not work with
compressed air if this can be avoided. Do not
move vehicle unless absolutely necessary.
Disconnected electrical connectors: Keep clean
and dry. Connect only when dry.
Pa
ge 5 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

24-4
Technical data

Engine identification

APB
Idling speed
Not adjustable - controlled by Idle Air Control (IAT)

750 - 850 RPM
Engine speed (RPM) limitation
via fuel injector shut-off approx: 6800 RPM
Fuel pressure at idle speed Vacuum hose
connected
approx. 3.5 bar positive pressure

Vacuum hose
disconnected
approx. 4.0 bar positive pressure
Residual pressure after 10 minutes at least 2.5 bar positive pressure
Fuel Injectors Spray pattern Multi-hole nozzle (same on all injectors)

Injection qty. (30 secs.) 135 - 165 ml

Resistance
(room temperature)
1)
13.5 - 15.5
1) When the engine is at operating temperature the resistance is increased by approx. 4 - 6 .
Pa
ge 6 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

24-5


Component locations, overview

Components A to I are not shown in the exploded
drawing.
A - Brake Light Switch -F- and Brake Pedal
Switch -F47-
In footwell on pedal bracket near brake
pedal
B - Diagnostic connectorIn front knee protection, driver side
C - Fuel Pump (FP) relay -J17-Relay position 4 of central electrics left side
under dash panel
D - Clutch Vacuum Vent Switch -F36In footwell on pedal frame
E - Throttle Position (TP) Sensor -G79-
and Sender -2- for accelerator pedal
position -G185 In footwell on accelerator pedal (both
senders are installed in one housing)
Pa
ge 7 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

24-6


Repair Manual, Fuel Supply System, Repair
Group 20, Components of EVAP system servicing
F - Electronic Power Control (EPC)
warning light
In instrument cluster (Significance of light
Page 24
-139
)
G - Leak Detection Pump (LDP) -V144
Below left rear wheelhousing liner
H - Oxygen Sensor (O2S) Behind Three
Way Catalytic Converter (TWC) -G130
with Heater for Lambda-probe 1 -Z29
This oxygen sensor is accessible from
below when vehicle is lifted
I - Oxygen Sensor (O2S) 2 Behind Three
Way Catalytic Converter (TWC) -G131
with Heater for Lambda-probe 2 -Z30 This oxygen sensor is accessible from
below when vehicle is lifted
Pa
ge 8 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1