A4 Mk1
Checking electronic engine power control (electronic throttle)
Performing adaptation of throttle valve control unit
The adaptation process enables the engine control unit to learn the various positions of the throttle valve control unit with the ignition switched on and the engine not running. these positions are stored in the control unit. The feedback signal indicating the position of the throttle valve comes from the two throttle valve drive angle senders. An adaptation must always be performed if the throttle valve control unit (J338) or the engine control unit is removed and refitted or replaced, or if the voltage supply to the engine control unit is interrupted. The learning process (adaptation process) is performed:
Note: Engine will not start during automatic adaptation. Test conditions
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After the Q key is pressed, the throttle valve actuator is first disconnected from the electricity supply. In this condition, the throttle valve is pulled into an emergency running position by a mechanical spring which is located in the throttle valve control unit. The values supplied by the two angle senders in this emergency running position are stored in the engine control unit. The throttle valve is then opened by a predetermined amount. When this value is reached, the throttle valve actuator is again disconnected from the electricity supply. The mechanical spring should then close the throttle valve to the previously learnt emergency running position within a specified period of time (spring test). The throttle valve actuator then closes the throttle valve; the values supplied by the angle senders in the throttle valve control unit are stored in the engine control unit. If the engine control unit disconnects the throttle valve actuator from the electricity supply while the vehicle is being driven, the result will be an increased and fluctuating idling speed and a very poor throttle response.
Note: The deciding factor is not how the learning stage counter (display zone 3) behaves during the adaptation process, but that specified value in display zone 4 "ADP OK" has been attained after adaptation. "ADP" in display zone 4 stands for "Adaptation". Note: If the adaptation is interrupted by the control unit, the reason could be one of the following:
When adaptation process is interrupted, message "Function is unknown or cannot be carried out at the moment" is displayed on tester. The next time the ignition is switched on (for several seconds), the adaptation process is automatically performed again.
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