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Pre-catalyst lambda probe and regulation: testing > < Function test

Leon Mk2

Idling test
Idling test
  Note!
t  Idling revs, ignition timing and CO content cannot be adjusted.
t  Idling revs are regulated to target values by the throttle valve drive in conjunction with the DIS function.
t  CO content is adjusted to the target value by lambda regulation. Through self-diagnosis possible faults in lambda regulation are found and stored in the fault memory.
Special tools and workshop equipment required
   
t  Fault reader -V.A.G 1551- or Vehicle systems checker -V.A.G 1552- with Lead -V.A.G 1551/3B-
Test conditions
l  Exhaust system, airtight between the cylinder head and catalyst.
l  All electrical consumers, for example lights and heated rear window, must be off.
l  On vehicles with air conditioner, the AC must be off.
l  Coolant temperature, 80 °C minimum → Anchor, display field 3.
Test process
–  Connect the -V.A.G 1551- (V.A.G. 1552). Start the engine and enter “address code” 01 to select the engine control unit. (Fault reader: Connecting and selecting the engine control unit → Chapter.).
–  Consult the fault memory; if necessary eliminate the fault and clear the memory → Chapter, Fault memory: consulting and clearing.
–  Then:
t  Leave on fault reader -V.A.G 1551-.
t  Let the engine continue idling.
  W00-0459
The display reads:
–  Press 0 and 4 for the function “Start basic settings” and press Q to confirm the entry.
  
Rapid data transmission             HELP
Select function XX
The display reads:
–  Press 0, 0 and 1 for “Display group number 1” and press Q to confirm the entry.
  
Basic settings                      HELP
Enter display group number XXX
The display reads: (1...4 = display fields)
  Note!
In the function “System in basic settings”, the activated charcoal filter solenoid valve -N80- is closed and the air conditioning compressor is off.
–  Check the conditions for basic settings in display field 4: Target value: 1x111111 (Meaning of the numbers → Anchor).
–  Briefly raise engine revs (throttle burst) and then let it idle for 2 minutes.
Test idling revs
–  Change to display group 56 as follows:
–  Press C.
–  Press 0, 5 and 6 for “Display group number 56” and press Q to confirm the entry.
  
System in basic settings   1       ->   
         1         2         3         4
The display reads: (1...4 = display fields)
–  Check the engine load states in display field 4. Target value: x x 0 x 0 (Meaning → Anchor).
–  Check target idling revs in display field 2. Target value: 850 rpm
–  Check idling revs in display field 1. Target value: 810...890 rpm
  Note!
During the idling test the activated charcoal filter solenoid valve and air conditioning are deactivated and lambda regulation self-adaptation begins.
–  Press →.
–  Press 0 and 6 for the function “End data transmission” and press Q to confirm the entry.
If idling revs are not reached:
–  Adapt the engine control unit to the throttle valve drive unit → Chapter.
–  Run a road test.
Take the necessary precautions during road tests → Chapter.
–  Consult the control unit fault memory again.
–  Repeat the idling test.
If the target values are still not reached:
–  Test the throttle valve drive unit → Chapter.
–  Test the engine load states → Chapter.
–  Test the intake system for infiltrated air → Chapter.
–  Test the signals from/to the air conditioner → Chapter.
  
System in basic settings   56      ->   
         1         2         3         4

Pre-catalyst lambda probe and regulation: testing > < Function test