Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle air control (IAC) valve (LH 2.2)





The idle air control valve allows a controlled volume of air to by-pass the throttle butterfly. The volume of air is determined by the degree of opening of the idle air control valve, which is controlled by signals from the LH control module.

The idle air control valve is a rotary slotted valve with a built-in two-stage motor that maintains a continuous reciprocating action, turning the valve through a maximum angle of 900.

Together with the mass air flow sensor system, automatic idle control has been introduced to give:
- steadier engine speed
- better cold-starting and warm-up performance
- increased idling speed on engagement of the air conditioning system
- compensation for reduced engine speed due to a heavier load from the steering servo pump and alternator charging and when the car is driven at high altitudes
- a deceleration function.