1997 AUDI A4 APB Engine Motronic Multiport Fuel Injection System Servising Workshop Manual

24-63


Note:
Ground (GND) from the ECM is present at terminal 3 of connector.
If specified value is not obtained, check wire connections Page 24
-74
. - Connect multimeter to terminal 2 and terminal 3 of connector for
voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage

If specified value is not obtained, check wire connections Page 24
-74
. - Connect multimeter to terminal 3 and terminal 1 of connector for
voltage measurement.
- Switch ignition on.
Specification: approx. 5 volts.
Pa
ge 73 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

24-64

Wire connections for Mass Air Flow (MAF)
sensor, checking (Hitachi MAF sensor)

Note:
Signal wire is also checked during wire test.

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-20
.

The following wire connections must be checked for short circuit to B+,
Ground (GND) and for open circuit Connector for Mass Air Flow (MAF)
sensor -G70-
VAG1598/31 test box
terminal
1 53
3 27
4 29
Pa
ge 74 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

24-65

Voltage supply for Mass Air Flow (MAF)
sensor, checking (Bosch MAF sensor)

Note:
Voltage is supplied to Mass Air Flow (MAF) sensor from Fuel Pump (FP)
relay.
If there is no battery voltage.
Electrical Wiring Diagrams, Troubleshooting & Component Locations - Disconnect connector from Mass Air Flow (MAF) sensor.
- Connect multimeter to terminal 2 of connector and engine Ground
(GND) for voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage
- Check wire connection from terminal 2 of connector to Fuel Pump (FP)
relay via fuse for open circuit and short circuit to Ground (GND), repair
if necessary.
Pa
ge 75 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

24-66


Note:
Ground (GND) from the ECM is present at terminal 3 of connector.
If specified value is not obtained, check wire connections Page 24
-74
. - Connect multimeter to terminal 2 and terminal 3 of connector for
voltage measurement.
- Operate starter briefly.
Specification: approx. battery voltage

If specified value is not obtained, check wire connections Page 24
-74
. - Connect multimeter to terminal 3 and terminal 4 of connector for
voltage measurement.
- Switch ignition on.
Specification: approx. 5 volts.
Pa
ge 76 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

24-67

Wire connections for Mass Air Flow (MAF)
sensor, checking (Bosch MAF sensor)

Note:
Signal wire is also checked during wire test.

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-20
.

The following wire connections must be checked for short circuit to B+,
Ground (GND) and for open circuit Connector for Mass Air Flow (MAF)
sensor -G70-
VAG1598/31 test box
terminal
3 27
4 53
5 29
Pa
ge 77 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

24-68

Wire resistance: max: 1.5 Ohm

- Also check all wires for short circuit to each
other.

Specification: infinite Ohms (no continuity)

- If the voltage supply and the wire connection are
OK, replace Mass Air Flow (MAF) sensor -G70-.
Pa
ge 78 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

24-69


Display fields

1 2 3 4
Display Group 002: Intake air mass at idling speed with engine at operating temperature
Display xxx RPM xx.x %
x.x ms
xxx.x g/s
Indicates Engine
speed
(in steps of
40 RPM) Load
Average injection
period Air mass
Work range min.: 750
rpm
max.: 6800
rpm min.: 15
%
max.:
175 % min.: 2.0 ms
max.: 19.0 ms min.: 3.0 g/s
max.: approx: 225g/s
Specification 750 - 850
rpm 15.0 -
25.0 % 2.0 - 4.0 ms1.
3.0 - 4.5 g/s
Note --- ---
If readout does not match
specification, see table for display
field 3 Page 24
-70

If readout does not match
specification, see table for display
field 4 Page 24
-71

If the specification is obtained:

-
Press button.
- Press buttons -0- and -6- to select function "End
Output" and confirm entry with -Q- button.
Pa
ge 79 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

- Switch ignition off.
Pa
ge 80 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