Idle Air Control (IAC) Valve for LT1 and LT4
This is from the 1994 GM Factory Serive Manual, Book
IDLE AIR CONTROL (IAC) VALVE
Remove or Disconnect
Electrical connector from IAC valve.
2. IAC valve assembly attaching
3. IAC valve assembly.
NOTICE: On IAC valves that have
been in service: Do not push or pull on the IAC valve pintle. The force
required to move the pintle may damage the threads on the worm drive.
Also, do not soak IAC valve in any liquid cleaner or solvent, as damage
Clean and Inspect
Clean IAC valve and
O-ring sealing surface, pintle, valve seat and air passage.
The IAC valve may be cleaned using GM cleaner 1052626 or GM X-66A. Use a
shop towel or parts brush to remove heavy deposits.
spots on the pintle or seat are normal, and do not indicate misalignment
or a bent pintle shaft.
If air passage has heavy deposits,
remove throttle body for complete cleaning.
Inspect IAC valve
and O-ring for cuts, cracks, or distortion. Replace if
If installing a new IAC valve, be
sure to replace with an identical part. IAC valve pintle shape and
diameter are designed for the specific application.
installing a New IAC Valve)
Distance between tip of IAC valve
pintle and mounting surface.
If more than 28 mm, use finger
pressure to slowly retract the pintle. The force required to retract the
pintle of a new valve will not cause damage to the valve.
1. Lubricate IAC valve O-ring with clean engine oil.
IAC valve assembly.
3. IAC valve attaching
IAC valve attaching screws to 3 N-m (27
4. Electrical connector to IAC valve
5. Reset IAC
valve pintle position:
A. Depress accelerator pedal slightly.
Start engine and release accelerator pedal, run engine for 5
C. Turn ignition “OFF” for 10 seconds.
Restart engine and check for proper idle operation.