Cherokee 2WD L6-242 4.0L VIN S MFI (1992)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
IAT And TPS Sensors
LOCATION
Idle Air Control (IAC) motor is mounted on throttle body.
PURPOSE
Motor maintains optimum idle speed under varying engine loads, and prevents deceleration die out.
OPERATION
The Automatic Idle Speed (AIS) motor controls air flow through a passage connected to both intake manifold plenums. The engine controller
maintains engine idle speed, by adjusting the IAC motor to compensate for engine load or ambient conditions.
The AIS varies the amount of air that is allowed to bypass the throttle blades. It does this by extending or retracting the AIS pintle into the idle air
passage. The further the AIS pintle protrudes into this passage the slower the idle speed, and the less the IAC pintle protrudes the greater the idle
speed.
Deceleration stall is also prevented by increasing the airflow when the throttle is closed suddenly
The engine controller calculates proper idle speed using information from throttle position, vehicle speed, and coolant temperature sensors and
brake, and neutral/safety switches.