GM Bonneville/Eighty Eight/LeSabre 1986-1999
Engine idle speeds are controlled by the PCM through the Idle Air Control (IAC) valve mounted on the throttle body. The PCM sends voltage pulses to the IAC motor windings causing the IAC motor shaft and pintle to move in or out a given distance (number of steps) for each pulse (called counts). The movement of the pintle controls the airflow around the throttle plate, which in turn, controls engine idle speed. IAC valve pintle position counts can be observed using a scan tool. Zero counts correspond to a fully closed passage, while 140 counts or more corresponds to full flow.
Idle Air Control Valve
REMOVAL & INSTALLATION