Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Air Control Valve:



A new, compact twin-coil control valve is used. It is directly screwed onto the throttle housing without additional air ducting hoses.

In conjunction with the DME control unit, the basic quantity of air required for the corresponding operating condition of the engine is supplied via the control valve bypass. Deviation from a programmed basic quantity of air when the engine is at idle speed is adaptively corrected by the DME control unit under the following conditions:
- Idle speed
- Zero vehicle speed
- Engine temperature > 79.5°C

In conjunction with the DME control unit, the idle air control valve also regulates the idle speeds required for the different operating conditions of the engine.

Programmed Idle Speeds: (A Engine speed B = Engine temperature):




Engine idle speeds, manual transmission




Engine idle speed with Tiptronic transmission, driving position selected




Engine idle speed with Tiptronic transmission, shift lever set to P or N




Engine idle speed with Tiptronic transmission, driving position selected and air conditioning switched on.

Idle Speed Regulation Via Supply Voltage:
The following special function has been programmed in order to improve the load balance of the alternating current generator: if the supply voltage drops below 11.03 Volts for longer than 8 seconds at idle speed, the idle speed is adjusted to 850 rpm by the DME control unit and the idle air control valve. With Tiptronic vehicles, this function is only active if no drive position has been selected

If an undervoltage is detected when a driving position has been selected, the increased idle speed only becomes active in the next idle cycle. Downward adjustment of the increased speed after undervoltage is performed after the next transition from partial load to idle speed if the supply voltage was higher than 11.03 Volts.