Skylark L4-138 2.3L DOHC VIN D MFI QUAD 4 (1989)
^ The ECM normally resets the IAC valve pintle position once during each ignition cycle, when vehicle speed increases above 20 mph on moderate
acceleration. During the next reset, the ECM commands the IAC valve pintle to retract completely, then move "IN" to the seated position (to establish
the zero count position), and then back out the desired position. If, after the reset, the ECM is able to control the idle speed within the calibrated count
range, the IAC valve will not be reset again until after the ignition has been turned "OFF," the engine restarted and then the car driven above 20 mph. If
the ECM is not able to control idle speed within the calibrated count range after the first reset, the ECM assumes the IAC valve is "lost," and enables
another reset to occur. This will continue until the pintle position is learned.
^ If the IAC valve is disconnected and reconnected while the engine is running, the resulting IAC valve counts may not correspond with the actual IAC
valve position. When servicing the IAC valve, it should only be disconnected or connected after the ignition has been "OFF" for at least 10 seconds.
This allows time for the ECM to move the IAC valve to the 150 count position where it is "parked" while the ignition is "OFF." If this procedure is not
followed, the ECM will lose track of the IAC valve position resulting in starting or idle control problems until the IAC valve is reset by the ECM, and
pintle position is relearned.
^ For diagnosis and testing procedures, see COMPUTERIZED ENGINE CONTROLS.
