Audi Workshop Service and Repair Manuals

The adaption process enables the engine control unit to learn the different positions of the throttle valve 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 angle senders for throttle valve drive.

If the throttle valve control part -J338 or the engine control unit is removed and refitted or replaced, or if the power supply to the engine control unit is interrupted, an adaption must be performed.

The learning process (adaption process) is carried out:

• ◆ Automatically if the ignition is switched on for at least 6 seconds without operating the starter or depressing the accelerator, and if the engine control unit registers a "learning requirement". (In this case, however, there is no way of knowing whether the adaption process was successful or not.) The engine control unit will register a learning requirement if the previously stored voltage readings from the angle senders do not correspond (within a certain tolerance range) to the new voltage readings.
• ◆ By selecting "Basic setting" (function 04), Display Group 60 with the ignition switched on.

Test conditions

• ● No faults stored in fault memory
  , Interrogating fault memory
• ● Engine not running, ignition switched on
• ● Accelerator not depressed
• ● Coolant temperature between 5°C and 100°C
• ● Intake air temperature less than 100°C
• ● Power supply to engine control unit more than 11 V
  Testing

• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 (or fault reader V.A.G 1551) and select engine electronics control unit by entering address word "01" ( => Page 01-3.)
  When doing this the ignition must be switched on.

• ‒ Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with Q key.

• ‒ Press keys 0, 6 and 0 for Display Group 60 and confirm entry with Q key.

When the Q key is pressed the current supply to the throttle valve positioner will be disconnected.

In this condition the throttle valve is pulled into an "emergency running" or default position by a spring in the throttle valve control part. The values supplied by the two angle senders for this position are stored in the engine control unit.

The throttle valve is then opened by a predetermined amount. As soon as it reaches this position the current supply to the throttle valve positioner is again disconnected. The spring should then close the throttle valve mechanically to the previously learned default position within a specified period of time (spring test).

The throttle valve positioner then closes the throttle valve and the values supplied by the angle senders in the throttle valve control part are stored in the engine control unit.

If the engine control unit disconnects the current supply to the throttle valve positioner while the vehicle is being driven, the result will be an increase in idling speed with fluctuating engine rpm (hunting) and very slow throttle response.

• ‒ Check display values for throttle valve control part (display zones 3 and 4).

Note:

The abbreviation "ADP" in display zone 4 stands for "Adaption".

Note:

If the adaption process is interrupted by the control unit, the cause could be one of the following:

• ◆ The throttle valve is unable to close completely (e.g. because of dirt)
• ◆ Battery voltage too low.
• ◆ Throttle valve control part or wiring is defective.
• ◆ The engine was started or the accelerator depressed during the adaption process.
• ◆ Distortion of throttle valve housing (check bolts)

When the adaption process is interrupted the message "Function is unknown or cannot be carried out at the moment" will appear on the fault reader display. The adaption process will start again automatically the next time the ignition is switched on (for several seconds).

• ‒ End the engine basic setting by pressing the⇒ key.