Syclone V6-262 4.3L Turbo (1991)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
Idle Air Control Valve
All engine idle speeds are controlled by the ECM/PCM through the Idle Air Control valve mounted on the throttle body. The ECM/PCM sends voltage
pulses to the IAC motor windings causing the IAC motor shaft and pintle to move in and out a given distance (number of steps) for each pulse, (called
counts).
This movement controls airflow around the throttle plate, which in turn controls engine idle speed, either cold or hot. IAC pintle position counts can be
seen using a "Scan" tool. 0 counts correspond to a fully closed passage, while 140 counts or more (depending on application) corresponds to full airflow
through the throttle body bypassing the throttle blade.