1996 AUDI A4 air condition

24-27

Idle speed, checking


Test conditions

No leaks in exhaust system
Coolant temperature at least 80 C

Electrical consumers switched off (radiator
fan must not run during the check)
A/C switched off
Pressure gauge not connected
Selector lever in position P or N (vehicles
with automatic transmission)

Checking idle speed

Notes:
The idle speed cannot be adjusted.
The idle speed is tested during the basic setting
of the engine.
Pa
ge 31 of 90 Motronic Multi
port Fuel In
jection
(MFI
) system, servicin
g
11/22/2002 htt
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play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1

24-29
Notes:
System in Basic Setting 56
1
2
3
4

Indicated on display: (1 - 4 display zones) - Check whether the engine speed shown in display field 1 (actual
engine speed) is within the specified tolerance range (750 - 850 RPM).

Display fields

1 2 3 4
Display Group 056: Idle speed stabilization with engine idling at operating temperature
Display
xxx RPM
xxx RPM x.x % xxxxxxx
Indicates
Engine speed (actual)
Engine speed
(specified) Idling speed control-
torque change Operating conditions
Specified
value 750 -850 RPM
800 RPM x.x % 0 0 0 0 0
Note
If readout does not match
Specified value Page 24
-31

Relevance of figures
Page 24
-32

The value shown in display field 1 is the actual engine speed.
The value shown in display field 2 (specified engine speed) is a theoretical value calculated by the engine control module.
See note on next page:
Pa
ge 34 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

24-35

- If pressure is higher than specification, check
return pipe for damage (e.g. pinching) and
renew if necessary.

Note:
During the following test, do not allow the engine
to run for too long with the vacuum hose
disconnected, otherwise the increased fuel
pressure will enrich the air/fuel mixture and may
cause the lambda control limits to be exceeded.
This would be stored as a fault in the fault
memory.

- Start the engine and run at idling speed.

- Switch off electrical consumers (air conditioner
etc.).

- Re-connect vacuum hose to fuel pressure
regulator and observe drop in pressure on
pressure gauge.
Pa
ge 40 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

24-40

Checking voltage supply

Test conditions

Fuse for injectors OK

Electrical Wiring Diagrams, Troubleshooting &
Component Locations

- Disconnect harness connector from fuel injector
to be tested.

- Connect diode test lamp (for measuring voltage) between Ground
(GND) and socket 1 of connector.
Pa
ge 47 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

24-43

Fuel injection volume, fuel injector
leakage and spray pattern of injectors,
checking


WARNING!

Fire hazard! 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 pulling off the hose or cap.

Test conditions

Fuel pressure OK; testing Page 24
-33
.
To reach the fuel rail, the following steps must be
performed on vehicles with manual transmission
(without secondary air injection). On vehicles
with automatic transmission (with secondary air
injection) are minor differences in the work
procedure.

Several hoses must now be disconnected: - Unscrew bolts on air duct at points indicated (arrows) and remove air
duct.
- Absolute cleanliness must be maintained.
Pa
ge 51 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

24-70
Reading Display Group 002 Display field
3
Possible cause of malfunction
Corrective action
Less than 2.0
ms
Lower values can only occur when vehicle is on fuel-
shut off (overrun)
More than 4.0
ms Load on engine due to ancillaries- Eliminate load (air conditioner, power
steering, alternator)

Rough idle (engine not running on all cylinders)- Check spark plugs
- Check fuel injectors Page 24
-39


Throttle Valve Control Module -J338 faulty- Check Throttle Valve Control Module
Page 24
-139

Pa
ge 81 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