fuel AUDI A4 1999 B5 / 1.G APB Engine Charge Air System With Turbocharger Workshop Manual

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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- Connect T-piece with measuring hose of turbocharger tester VAG 1397
A to fuel pressure regulator -arrow-.
- Route measuring hose under rear edge of hood and into passenger
compartment via right-hand window.
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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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21-17

- 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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21-21

- Initiate output Diagnostic Test Mode (DTM) and
activate recirculating valve for turbocharger -
N249-.

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

Output diagnostic test mode Recr. valve for turbocharger -N249

Indicated on display
If valve does not click:
If valve does not open and close properly: Valve must click...
...and must open and close (can be tested by blowing into assisting
hose).
- Check internal resistance of valve.
- Replace recirculating valve for turbocharger -N249-.
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21-23

Checking voltage supply

Note:
Voltage is supplied to the recirculation valve via
the Fuel Pump (FP) relay.

Test requirement:

Fuse for recirculation valve OK

- Disconnect connector at valve.

- Connect VAG1527B voltage tester as follows:Harness connector terminal
Measure to
1 Engine Ground (GND)
- Operate starter briefly.

LED must light.
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21-24
If LED does not light:

- Check wire connection from terminal 1 to Fuel
Pump (FP) relay via fuse for open circuit.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
- Repair open circuit if necessary.
If wire connection is OK:

- Check Fuel Pump (FP) relay.

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

If LED lights:

- Check activation, Page 21
-25
.
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21-25

Checking activation

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

If LED does not blink or if it remains constantly lit:
Repair Manual, 2.7 Liter V6 5V BiTurbo Fuel Injection & Ignition,
Engine Code(s): APB, Repair Group 24
- Connect VAG 1527B voltage tester to connector terminals 1 (B+) and
2.
- Initiate output Diagnostic Test Mode (DTM) and activate recirculating
valve for turbocharger -N249-.

LED must blink.
- Connect VAG 1598/31 test box at wiring harness to ECM. Do not
connect ECM.

- Check the following wire connections for open circuit and short circuit
to Ground (GND) and B+: Harness connector terminal
VAG 1598/31 test box
Bushing
2 9
- Repair open circuit or short circuit if necessary.
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