AUDI A4 1999 B5 / 1.G AWM Engine Charge Pressure Leak Test User Guide

With VAS 5051 diagnostic tool connected:

- Erase DTC memory.
If smoke generator was not used to fill the
system with smoke:

- Apply soapy water solution or equivalent to
intake system connections.
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Note:
An ultrasonic detector may also be used to
detect extremely small leaks.

- Inspect intake system connections for leaks.

- Repair any leaks found.

- Remove tester.

- Remove plug from crankcase ventilation hose.

- Remove air pressure adapter.
With VAS 5051 diagnostic tool connected:

- Erase DTC memory.
Pa
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Mechanical air recirculation valve,
checking


Note:

The mechanical air recirculation valve is
upstream of the exhaust turbocharger. It is
opened via vacuum by the recirculating valve
for turbocharger -N249- under conditions of
overrun, idling and partial load. This reduces
the charge pressure upstream of the throttle
valve. A high turbocharger speed is thus
maintained.
Check the air recirculation valve if the engine is
not producing full power, or jerking when the
throttle is opened and closed.

Special tools and equipment

Hand vacuum pump VAG 1390
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Test sequence

If the air recirculation valve does not open and close as specified, or if the
valve plate does not seal properly when the valve is closed: - Attach vacuum pump VAG 1390 to air recirculation valve.
- Actuate hand vacuum pump.
Air recirculation valve should open -arrow-
- Operate air vent valve on vacuum pump after about 30 seconds.Air recirculation valve should close -arrow-
- Replace air recirculation valve and attach hose connections with hose
clamps.
Pa
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Recirculating valve for turbocharger -
N249-, checking

Special tools and equipment

VAG 1526 A
VAG 1527 B
VAG 1594 A
VAG 1598/31
VAS 5051 with VAS 5051/1
- or
VAG 1551 with VAG 1551/3 A
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Test requirements:

Vehicle diagnostic, testing and information
system VAS 5051 or VAG 1551 Scan Tool
connected.

Test sequence

Note:
The recirculating valve for turbocharger -N249-
and the wiring connections are monitored by the
engine control module.

- Read Diagnostic Trouble Code (DTC) memory
of engine control module.
If a DTC relating to the recirculating valve for
turbocharger -N249- is displayed:

Note:
The illustration shows bottom view of removed intake line. - Remove hoses of recirculating valve for turbocharger -N249- (-1-). The
electrical connector remains plugged in.
Location: below intake line
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- Connect auxiliary hose to valve connector marked with an arrow.
- Initiate output Diagnostic Test Mode (DTM) and activate recirculating
valve for turbocharger -N249-.
Output Diagnostic Test Mode Recircul. valve for turbochar
ger -N249-

Display:
If the injector does not click:
If valve does not open or close properly:
The valve should click ... ... and must open and close (check by blowing into the auxiliary
hose).
- Check internal resistance of valve.
- Replace recirculation valve for turbocharger -N249-.
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Checking internal resistance

- Disconnect connector from recirculation valve for turbocharger -N249-
(-1-).

If specified value is not attained:
If specified value is attained: - Connect multimeter to injector to measure resistance.
Specified value: 27 to 30
- Replace recirculating valve for turbocharger -N249-.
- Check power supply.
Pa
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Checking power supply

Note:
The power supply for the recirculating valve is via
the fuel pump relay.

Test requirements:

Fuse for recirculating valve OK.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Fuel pump relay OK.

Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24


- Disconnect wiring connector from valve.

- Connect voltage tester VAG 1527 B as follows:Connector
Measure to
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contact
1 Engine Ground
- Operate starter briefly.
The LED must light up.
Pa
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