IAC sticking...effect on part throttle driving?


Mar 31, 2005
Boston, MA
This question is about my truck, but I think it would relate to most cars.

I know that the IAC valve on my 96 4.0 Ranger is sticking a little. Not enough to make it stall, but enough that it gives it some hesitation and bucking at idle every once in a while. I cleaned it, but it came back. I need a new one...

Anyways, since the IAC valve is partially sticking, does this effect performance/mileage at part throttle cruising? I havent noticed any difference except when the engine is coming just off idle.

Do computers monitor or account for air that is coming through the IAC valve at part throttle?
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The IAC is essentially useless when the throttle blade is open any degree (a closed Throttleblade is a severe impediment to air flow to the motor, hence having a means of bypassing it).

The IAC will play into the dashpot function while moving and that's a time when I'd be worried if your idle is dropping too low or too fast (having a car stall while downshifting for a sharp turn, for instance, could really suck).

Good luck.