diagnostic AUDI A4 1995 B5 / 1.G APB Engine Ignition System Checking

28-1


Ignition system, checking

General notes on ignition system


Always switch off the ignition before connecting
or disconnecting the battery, otherwise the
engine control module may be damaged.
The engine control module is equipped with On
Board Diagnostic (OBD).
For trouble-free operation of the electrical
components a voltage of at least 11.5 V is
necessary.
During some of the tests it is possible that the
control module will detect and record a
malfunction. The DTC memory must therefore
be checked and if necessary erased when all
tests and repair work have been completed.
After completing troubleshooting, repairs or
component tests, it is possible that the engine
will start, run for a short period and then cut out.
If this happens it may be that the immobilizer is
blocking the engine control module. In such
cases the DTC memory must be checked and if
necessary the control module must be adapted.
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28-5

Ignition coils, checking


Note:
Misfiring is recognized by the On Board
Diagnostic (OBD). This means a non working
cylinder is stored with the cylinder number in the
DTC memory. This has an advantage in case of
a malfunction the trouble shooting procedure can
be started at a certain cylinder. Check the DTC
memory of the Engine Control Module (ECM)
before commencing trouble shooting.

Test conditions

No DTCs stored relating to any of the fuel
injectors
Determine a non working or misfiring cylinder as
follows:
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28-17

Intake Air Temperature (IAT) sensor -
G42, checking

Location of sensor and connector Page 24
-5 .

- Connect vehicle diagnostic, testing and
information system VAS 5051 or VAG1551 scan
tool and select engine electronics control
module by entering address word "01" Page
01
-9 . When doing this the ignition must be
switched on.
Rapid data transfer
HELP
Select Function XX

Indicated on display
- Press buttons -0- and -8- to select function "Read Measuring Value
Block" and confirm entry with -Q- button.
Read Measurin
g Value Block
HELP
Input Displa
y Group Number XXX

Indicated on display
- Press buttons -0-, -0- and -4- to select Display Group 4 and confirm
entry with -Q- button.
Read Measuring Value Block 4
1
2
3
4

Indicated on display: (1...4 display fields) - Check display value for intake air temperature sensor (display field 4):
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28-25

Engine Coolant Temperature (ECT)
sensor -G62, checking


Note:
Component location of coolant temperature
sensor Page 24
-5 .

Test conditions

Engine cold

- Connect vehicle diagnostic, testing and
information system VAS 5051 or VAG1551 scan
tool to vehicle and select engine electronics
control module by entering address word "01"
Page 01
-9 .

When doing this the engine must be at idle.
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28-50
If all the test results so far have been OK but a
malfunction related to the camshaft position
sensor (Hall sensor) is displayed again after
erasing the DTC memory as a test measure, the
following might be the cause:

- Rotor ring (trigger wheel) for camshaft position
sensor (Hall sensor) misaligned; test phase
position.

Checking phase position of Hall sensor

- Connect vehicle diagnostic, testing and
information system VAS5051 or VAG1551 scan
tool and select engine electronics control
module by entering address word "01" Page
01
-9 . When doing this the engine must be
idling.
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select function "Read Measuring Value
Block" and confirm entry with -Q- button.
Read Measurin
g Value Block
Input displa
y group number XXX

Indicated on display:
- Press buttons -0-, -9- and -3- to select "Display Group 093" and
confirm entry with -Q- button.
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28-52

Misfire recognition, checking


Test sequence

- Connect vehicle diagnostic, testing and
information system VAS5051 or VAG1551 scan
tool and select engine electronics control
module by entering address word "01" Page
01
-9 . When doing this the engine must be at
idle.
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -8- to select function "Read Measuring Value
Block" and confirm entry with -Q- button.
Read Measurin
g Value Block
Input displa
y group number XXX

Indicated on display
- Press buttons -0-, -1- and -4- to select "Display Group 014" and
confirm entry with -Q- button.
Read Measuring Value Block 14
1
2
3
4

Indicated on display
- Check misfire recognition.
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