Idle Speed Control

IDLING CONTROL
Idling speed is controlled by signals sent from the control module to a two-winding Idle Air Control (IAC) valve.

The automatic idling control function is adaptive, i.e. it adapts continuously to the changes taking place throughout the life of the engine. Such changes might be wear in the engine, dirt or leakage in the intake manifold or throttle body, etc.

The control module is programmed to maintain idling speed if the speed of the car is less than 3 km/h at the same time as the throttle position sensor indicates that the butterfly is in the idling position.

Engine speed compensation takes place when the AC is engaged, when DRIVE is selected on cars with automatic transmission and when the cooling fan cuts in.

Similarly, engine speed compensation takes place when the secondary air injection pump is engaged. In regard to the MOTRONIC 2.10.2 system, this only concerns B234i engines for the SE and US markets.

Idling speed for the MOTRONIC 2.10.2 system is 900 rpm.