Idle Speed/Throttle Actuator - Electronic: Description and Operation

PURPOSE
The Idle Air Control (IAC) valve controls engine idle speeds, both cold and warm engine conditions.

CONSTRUCTION
Three types of IAC valves are applicable:

Hitachi

Hitachi Idle Air Control (IAC) Valve And Solenoid:

Hitachi With Vent/Filter

Hitachi Idle Air Control (IAC) Valve And Solenoid:

Nippondenso

Nippondenso Idle Air Control (IAC) Valve Assembly:

OPERATION
The valve allows a monitored amount of air to pass around the throttle plate to control the following:

- Fast idle for cold engine start-up

- Idle dashpot

- Start-up without pumping the accelerator pedal

- Idle speed increase for an overheat condition

- Engine idle load correction