Safari Van AWD V6-262 4.3L VIN W CPI (1992)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
Idle Air Control (IAC) System
IAC Valve
IAC System
PURPOSE
To control engine idle speed and prevent stalling due to changes in engine load.
OPERATION
All engine idle speeds are controlled by the control module through the Idle Air Control (IAC) valve mounted on the throttle body. The control
module 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). Inward movement of the pintle = Decreased RPM =Lower Counts. Outward movement of the pintle = Increased
RPM = Higher Counts.
This movement controls airflow around the throttle plate, which in turn, controls engine idle speed, either cold or hot. IAC valve pintle position counts
can be seen using a Tech 1 scan tool. Zero (0) counts correspond to a fully closed passage, while 140 counts or more (depending on the application)
corresponds to full flow.
- Actual or "controlled" idle speed is obtained by the control module positioning the IAC valve pintle. Resulting idle speed is generated from the total
