Idle Speed Control

Idle Speed Control







The ECM determines idle speed by controlling an idle speed actuator (dual winding rotary actuator) ZWD 5.

The basic functions of the idle speed control are:
- Control the initial air quantity (at air temperatures < 0 C, the MDK is simultaneously opened)
- Variable preset idle based on load and inputs
- Monitor RPM feedback for each preset position
- Lower RPM range intake air flow (even while driving)
- Vacuum limitation
- Smooth out the transition from acceleration to deceleration

Idle speeds will vary (idle speed stabilization):
- During the warm up phase
- When Air conditioning is activated
- When a drive gear is selected
- When heating the passenger compartment
- At all electric fan speeds
- If nominal RPM is modified (idle speed increase) by DIS service function (if applicable)

Emergency Operation of Idle Speed Actuator:

If a fault is detected with the idle speed actuator, the ECM will initiate failsafe measures depending on the effect of the fault (increased air flow or decreased air flow).

If there is a fault in the idle speed actuator/circuit, the MDK will compensate to maintain idle speed. The EML lamp will be illuminated to inform the driver of a fault.

If the fault causes increased air flow (actuator failed open), VANOS and Knock Control are deactivated which noticeably reduces engine performance.