Leganza SE L4-2.2L DOHC D-TEC MFI (2001)
Idle Speed/Throttle Actuator - Electronic: Testing and Inspection
Idle Air Control System Check
Idle Air Control System Check
Circuit Description
The Engine Control Module (ECM) controls the engine idle speed with the Idle Air Control (IAC) valve. To increase the idle speed, the ECM pulls the
IAC pintle away from its seat, allowing more air to pass by the throttle body. To decrease the idle speed, it extends the IAC valve pintle toward its seat,
reducing bypass air flow. A scan tool will read the ECM commands to the IAC valve in counts. The higher counts indicate more air bypass (higher idle).
The lower counts indicate less air is allowed to bypass (lower idle).
Diagnostic Aids
If the idle is too high, stop the engine. Fully extend the Idle Air Control (IAC) valve with a IAC driver. Start the engine. If the idle speed is above 800
rpm, locate and repair the vacuum leak. Also, check for a binding throttle plate or throttle linkage or an incorrect base idle setting.
