1996 AUDI A4 APB Engine Charge Air System With Turbocharger Workshop Manual

21-15

- Road test vehicle.


Wide Open Throttle (WOT) must be
reached

- Measurement must be taken at Wide Open
Throttle (WOT).

Display fields

1 2 3 4
Display group 115: Charge air pressure regulation
Display 1 RPM % mbar mbar
Indicated Engine speed (RPM) Actual load Specified pressure Actual pressure
Specified value XXX Must not deviate more
than +/- 20 mbar
from specified
Note: Actual pressure must not deviate from specified
pressure by more than 20 mbar.
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21-16

- Select measuring value block 117.

- Check function of accelerator pedal in display
field 2 by briefly depressing pedal to Wide Open
Throttle.

Display fields

1 2 3 4
Display group 117: Charge air pressure regulation
Display 1 RPM
% % mbar
Indicated Engine speed (RPM)
Accelerator pedal
position Throttle valve angle Specified charge air
pressure
Specified value
0...100
Note: If the specified value 100% is not reached at
Wide Open Throttle (WOT):

- Check accelerator pedal.

- Select measuring value block 116.
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21-17

- Check correction factors in display fields 2 to
4.

Display fields

1 2 3 4
Display group 116: Charge air pressure regulation
Display 1 RPM
% % mbar
Indicated Engine speed (RPM)
Correction factor
Fuel Correction factor
Coolant temp. Correction factor
Intake air temp.
Specified value


Note: If display field 2 indicates a correction factor <0
%, fuel quality is probably incorrect.

- Fill tank with prescribed fuel quality.
If display field 3 indicates a correction factor <0
%, coolant temperature is too high (heat warning
lamp lit in instrument cluster) or the Engine
Control Module is receiving an incorrect
temperature signal from the instrument cluster.

- Check coolant temperature display.

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Repair Manual, Electrical Equipment, Repair
Group 90

Pa
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21-18
If display field 4 indicates a correction factor <0
%, intake air is too hot or the sensor for intake air
temperature is faulty.

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 24


- Select measuring value block 114.

Display fields

1 2 3 4
Display group 114: Charge air pressure regulation
Display
%
%
% %
Indicated
Specified engine load (without
correction) Specified engine load (after
correction) Actual
load Duty cycle
CAPR-cyclical
valve
Specified
value 136,0
134,3
137,5 55,2
Note: Load values in display fields 1 to 3 can deviate
from each other by up to 5 %. If specified values are not achieved in the
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measuring value blocks:

- Check the charge air pressure sensor -G31-.
Pa
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21-19


Recirculating valve for turbocharger -
N249-, checking

Special tools and equipment

VAG 1526A
VAG 1527B
VAG 1594A
VAG 1598/31
VAS 5051 with VAG 5051/1
- or
VAG 1551 with VAG 1551/3A
Pa
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21-20

Note:
The recirculating valve for turbocharger -N249
and wire connections are monitored by the
Engine Control Module (ECM).

- Connect VAS 5051 tester or VAG 1551 scan
tool and select control module for engine
electronics using "address word" 01. Engine
must run at idle for this.

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 01


- Check DTC memory of Engine Control Module
(ECM).

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel
Injection & Ignition, Engine Code(s): APB, Repair Group 01

If a Diagnostic Trouble Code (DTC) relating to
the recirculating valve for turbocharger -N249- is
displayed:

-
Disconnect hoses from valve; harness connector
Pa
ge 24 of 37 Char
ge air s
ystem with turbochar
ger
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