display AUDI A3 1998 8L / 1.G AEB ATW Engines Turbocharger System Workshop Manual

21-7


Note:
WARNING! - Turn turbocharger tester on and select measuring range -I- (absolute
pressure).
- Connect test hose to connection flange -I-.
Hoses must be connected so there is no possibility of leaks, otherwise
incorrect readings may result. Ensure test hose is not pinched at the hood and/or window.By pressing the memory button "M" on the turbocharger tester, the last
test value is stored until either memory button "M" is pressed again or
the turbocharger tester is shut off. A blinking comma in the display field indicates a value has been
stored. An arrow appears in the top left corner of the display field if the
turbocharger tester battery voltage drops below the allowed
specification. Before testing, drive vehicle briskly for at least 3 km (approx. 2 miles)
without frequent stops. Always use a second technician to take measurements via the
VAG1397A turbocharger tester when test-driving vehicle for this
test. Follow "WARNING!" Page 21
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VAG - ON BOARD DIAGNOSTIC
HELP
1 - Rapid data transfer2 - Blink code output

Indicated on display
1)
1) Operating modes 1 and 2 are displayed alternately
Note:
If nothing appears on display:
Scan tool operating instructions
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- 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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1
2
3
4
Interpreting values 1-4 in each display field Page 21
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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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