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Audi Workshop Service and Repair Manuals

Replacing engine control unit > < Checking control unit voltage supply
Motronic injection and ignition system (4-cyl.)
Engine control unit
Procedure after voltage supply open circuit

All values learnt by the engine control unit and the basic setting values as well as the readiness code will be erased if the voltage supply is interrupted. Therefore, depending upon the vehicle mileage it can lead to serious engine running problems.

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

  • ◆ Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/3

Work sequence

Perform the following operations after voltage supply open circuit:

  • ‒ Switch ignition on for at least 10 seconds.
  • ‒ Switch off ignition.
  • ‒ Adapt the engine control unit to the throttle valve control part
  • ‒ Perform idling check
    => Page 24-90

Note:

During the idling check the tank venting valve (N80) and the air conditioner are switched off and the Lambda regulation learning process is initiated.

  • ‒ Perform a longer test drive until the poor driving characteristics are eliminated.

Observe the valid safety precautions when carrying out a road test
.

  • During the road test the following operating conditions must be fulfilled:
    • ‒ The coolant temperature must exceed 80 °C .
    • ‒ When the temperature is reached, the operating conditions
          Idling
          Part throttle
          Full throttle
          Overrun
      must be attained several times.
    • ‒ At full throttle the speed must exceed 3500 rpm.

Replacing engine control unit > < Checking control unit voltage supply