Pickup 4WD V6-3137cc 3.1L (CPC) (1993)
Idle Air Control Valve: Description and Operation
IAC Valve
Idle Air Control Passage
PURPOSE
The Idle Air Control Valve (IAC) valve controls the engine idle speed, prevents stalling due to changes in engine load.
LOCATION
The IAC valve is mounted to the throttle body.
OPERATION
The IAC controls the amount of air bypassed around the throttle plate. This is actually a controlled vacuum leak. When more air is bypassed, idle
speed increases, when less air is bypassed, the idle speed decreases. The IAC valve accomplishes this by moving a conical shaped pintle "IN" (into
air passage) to decrease bypassed air and "OUT" (out 9of air passage) to increase bypassed air. This can be seen as counts displayed on a "Scan"
tool.
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Inward Movement of the pintle = Decreased RPM = Lower Counts.
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Outward Movement of the pintle = Increased RPM = Higher Counts.