engine AUDI A4 1997 B5 / 1.G APB Engine Charge Air System With Turbocharger Workshop Manual

21-1


Charge air system with
turbocharger

Turbocharger, removing and installing

Observe rules for cleanliness Page 21
-8 .

Notes:

Turbochargers must be replaced in pairs.
Manufacturing tolerances may prevent matched
operation.
All hose connections are secured with clips.
Charge air system must be free of leaks.
Replace self-locking nuts.
Replace all seals and gaskets

- Remove engine Page 10
-1 .

Removing right-hand turbocharger

- Remove cover panel from right-hand cylinder head cover -arrows-.
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21-7

Tightening torque

Bolted mountings Tightening
torque
Turbocharger 20 Nm
Intake line to cylinder head 10 Nm
Heat shield to turbocharger 10 Nm
Exhaust manifold to exhaust
pipe 25 Nm
Injector pipes 30 Nm
Intake pipe to engine
support 10 Nm
Oil pipe to turbocharger 15 Nm
Oil pipe to intake manifold 20 Nm
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21-10

Requirements for test:

Diagnostic Trouble Code (DTC) memory has
been interrogated

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


Output Diagnostic Test Mode (DTM) has
been performed
Engine oil temperature at least 60 C

All vacuum connections airtight

- Loosen bolts -arrows- and remove engine cover panel -B-.
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21-12

- Accelerate vehicle from 2000 RPM at full throttle
in fourth gear, and watch rev counter.

Note:
If no charge pressure is obtained and a throbbing noise can be heard in
the engine compartment, the causes can be as follows: - Press memory key -M- on turbocharger tester at 3000 RPM.

Specification: 1.550 ... 1.650 bar
Air recirculation valve faulty.Vacuum line to air recirculation valve leaking or has become
disconnected.
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21-14

Test sequence

Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition,
Engine Code(s): APB, Repair Group 01
- 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.
Rapid data transfer
HELP
Select function XX

When indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
Read measurin
g value block
Q
Input displa
y group number XXX

When indicated on display
- Press buttons -1-, -1- and -5- to select "display group number 115" and
press -Q- button to confirm input.
Read Measuring Value Block 115

Indicated on display (1...4 display fields)
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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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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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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
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