AUDI A4 1996 B5 / 1.G APB Engine Charge Air System With Turbocharger User Guide

- 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.
Pa
ge 11 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

21-11


Notes: - Switch on turbocharger tester and set measuring range selector switch
to position -I- (absolute pressure).
- Connect measuring hose to connection -I-.
Hose connections must be completely airtight, otherwise
measurements will not be correct. Ensure that measuring hose is not pinched at hood or side window.Pressing memory key M on turbocharger tester will store the last
measured value until memory key M is pressed again or tester is
switched off. The decimal point in the display flashes to indicate that the value is
being stored. If the battery voltage of the turbocharger tester drops below the
minimum level, an arrow will appear at the top left of the display. Before performing the test, drive the vehicle at a brisk speed for at
least 3 km (without stopping at traffic lights etc.). A second mechanic is required to note the readings on the tester
when the vehicle is moving. Observe safety notes Page 21
-9 .
Pa
ge 12 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

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.
Pa
ge 13 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

21-13

Charge air pressure regulation,
checking


Special tools and equipment

or
Test requirement:
WARNING!
VAS 5051 with VAG 5051/1VAG 1551 with VAG 1551/3ACoolant Temperature at least 80 C. During a road test in an airbag-equipped vehicle, test equipment
must always be fastened to and operated from the rear seat by a
second technician. When driving or riding in an airbag-equipped vehicle, NEVER hold
the scan tool or other test equipment in your hands or lap while in
motion. Objects between you and the airbag increase the risk of
injury in an accident.
Pa
ge 14 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

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)
Pa
ge 15 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

1
2
3
4
- Check charge air pressure regulation.
Pa
ge 16 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

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.
Pa
ge 17 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

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.
Pa
ge 18 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

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.

Pa
ge 19 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1

Repair Manual, Electrical Equipment, Repair
Group 90

Pa
ge 20 of 37 Char
ge air s
ystem with turbochar
ger
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.GE05.21.1