engine AUDI A6 1997 C5 / 2.G AEB ATW Engines Turbocharger System Workshop Manual

21-6

Test conditions:

Check DTC memory Repair Manual, 1.8
Liter 4-Cyl. 5V Turbo Fuel Injection &
Ignition, Repair Group 01
Perform output diagnostic test mode
(function 03)
Minimum engine oil temperature: 60 C
(140 F)

All vacuum connections are free of leaks

Test procedure

- Using T-fitting, connect VAG1397A turbocharger tester test hose to
front of intake manifold.
- Guide test hose over rear corner of hood through right window opening
into vehicle interior.
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21-8

Vehicles with manual transmission:

- Accelerate vehicle in 3rd gear at full throttle from
2000 RPM and watch tachometer.

Vehicles with automatic transmission: - At 3000 RPM press memory button "M" on turbocharger tester.
Specification: 1.37-1.47 bar (19.865-21.315 psi)
- Drive with selector lever in range 2.
- Accelerate to 3000 RPM and wait for transmission to shift into 2nd
gear.
- Press accelerator pedal to kickdown position (transmission will not shift
down at this vehicle/engine speed).
- At 4500 RPM, press memory button "M" on turbocharger tester.
Specification: 1.3-1.4 bar (18.85-20.30 psi)
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21-9

Note:
For vehicles with automatic transmission the
charge air pressure test may not always provide
a definitive reading of proper charge air pressure
regulation. If pressure readings are at the lower
end of the specified range, measure charge air
pressure control via load signal Page 21
-10
.

All vehicles:
If measured value is above or below specification
Repair Manual, 1.8 Liter 4-Cyl. 5V Turbo Fuel
Injection & Ignition, Repair Group 24.

Note:
If no charge air exists and a rumbling sound is
heard from the engine compartment, the causes
are as follows:

Charge pressure bypass valve
malfunctioning.
Vacuum line to charge pressure bypass valve
leaking or disconnected.
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21-11

- Press button 1 to select "Rapid data transfer"
operating mode 1.

- Start engine.Rapid data transfer
HELP
Select function XX

Indicated on display
Rapid data transfer
Q
01 - En
gine Electronics

- Press buttons -0- and -1- to insert "Engine Electronics" address word
01.
- Press -Q- button to confirm input.
06A906018.. 1.8l R4/5T MOTR HS 0.. Codin
g 04000
WSC 12345

VAG1551 scan tool display indicates control module coding.
-
Press button.
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select "Read Measuring Value Block"
function 08.
- Press -Q- button to confirm input.
Read Measuring Value Block
HELP
Input displa
y group number XXX

Indicated on display
- Press buttons -1-, -1- and -4- to input display group number 114 (114).
- Press -Q- button to confirm input.
Read Measuring Value Block 114

The "Read Measuring Value Block" displays four display fields.
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21-12

Interpreting display fields Read Measuring Value Block 114 1
2
3
4

Indicated on display:
Specification
Deviation between display field 2 and 3: 0.3 ms (max.)
Note:
If the OBD for the Engine Control Module (ECM) recognizes Diagnostic
Trouble Codes (DTCs) in charge air pressure regulation, duty cycle
(display field 4) will indicate a constant 5%.
Display
field Description
1 Not applicable
2 Specified engine load (after correction)
3 Current engine load
4 Duty cycle (actuation of wastegate bypass regulator valve
-N75-)
- Note values in display field 2 and 3 while vehicle is under steady
acceleration.
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21-13
Diagnostic Trouble Codes (DTC) for charge air pressure regulation Diagnostic
Trouble Code
(DTC) VAG1397A Display
VAG1551 Display
Possible causes
Charge air
pressure too
low
Measured value below 1.37
bar (19.9 psi) (vehicles with
manual transmission)
Measured value below 1.30
bar (18.9 psi) (vehicles with
automatic transmission)
Current engine load
(display field 3) less than
specified engine load
(display field 2) Duty cycle (display field 4)
close to 99%
Wastegate bypass regulator valve
-N75- malfunctioning Wiring to wastegate bypass
regulator valve -N75-
malfunctioning Wastegate in turbocharger stuck
in open position Leak between turbocharger and
intake manifold Turbocharger malfunctioning
Charge air
pressure too
high
1)
Measured value above 1.47
bar (21.3 psi) (vehicles with
manual transmission)
Measured value above 1.40
bar (20.3 psi) (vehicles with
automatic transmission)
Current engine load
(display field 3) higher
than specified engine load
(display field 2) Duty cycle (display field 4)
close to 0%
Vacuum diaphragm for wastegate
malfunctioning Hoses to vacuum diaphragm (for
wastegate) over wastegate
bypass regulator valve -N75-
leaking Vacuum diaphragm wastegate in
turbocharger stuck in closed
position
1) If charge air pressure is too high, the fuel supply is shut off to protect the engine. The engine misfires at high engine
speeds.
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21-15

WARNING!

Use only approved air fittings to adapt shop
air supply line to VAG 1687 tester.

Special tool VAG 1687/1 pressure adapter,
installing (1.8L Turbo)

- Separate intake hose from Mass Air Flow (MAF)
sensor assembly.

Special tool VAG 1687/1 pressure adapter, installing (2.7L BiTurbo)
Repair Manual, Maintenance; Air cleaner housing, cleaning; Air cleaner element, replacing
- Insert VAG 1687/1 pressure adapter in intake hose -black arrow- using
existing clamp (as shown).
- Remove crankcase ventilation tube from intake hose at -white arrow-.
- Remove upper air cleaner housing and hoses to intake manifold as
necessary

- Insert VAG 1687/1 pressure adapter in intake hose -white arrow- using
existing clamp (as shown).
- Disconnect engine crankcase ventilation hose from intake manifold -
black arrow-.
-
Plug intake manifold fitting (for crankcase ventilation hose) with
appropriate hose and metal plug using clamps supplied with VAG
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21-17

Special tool LKI9210 (Evaporative system
leak detector), preliminary set-up

- Connect smoke generator leads to vehicle
battery.

With system filled with smoke:
Special tool VAG 1687, connecting to pressure adapter VAG 1687/1
(1.8L Turbo)
For illustrations purposes VAG is shown lying in the engine compartment.
In practice the tool should be hung from the hood. - Turn valve to test -black arrow-.
- Press smoke generator button to fill system with smoke (see
instructions printed on tester).
- Remove smoke generator hose and connect VAG1687 quickly to
prevent smoke from leaking out Page 21
-17
.
- Connect VAG 1687 quickly to prevent smoke from leaking out.

VAG 1687 is shown connected to VAG 1687/1 -black arrow-
Shop air supply will be connected to VAG 1687 -at white arrow-
- Perform pressure test Page 21
-19
.
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21-18

Special tool VAG 1687, connecting to
pressure adapter VAG 1687/1 (2.7L BiTurbo)
For illustrations purposes VAG is shown lying in
the engine compartment. In practice the tool
should be hung from the hood.

- Connect VAG 1687 quickly to prevent smoke
from leaking out.

VAG 1687 is shown connected to VAG 1687/1 -black arrow-
Shop air supply will be connected to VAG 1687 -at white arrow-
- Perform pressure test Page 21
-19
.
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21-19

Performing pressure test:

- With outlet hose -1- of VAG 1687 connected to air pressure adapter:
- Attach shop air supply line to previously installed male fitting ( Page
21
-14
.

CAUTION! - Open valve -3- between regulator valve and gauge.
- Adjust test pressure up to 0.5 bar ( CAUTION below) by turning
regulator valve -2-.
DO NOT pressurize the system above 0.5 bar!Doing so may force oil into the intake system which can damage
the engine.
- Slowly open outlet valve -4- (after gauge) to test hose connections.
- Observe pressure gauge for a drop in pressure.
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