Idle Air Control Valve explanation needed?

[Meestahbig]

Hi,

I'm still chasing my very intermittent stall. It only happens when braking and transitioning from open throttle to idle. I only recently noticed RPM bouncing a bit when it drops below 1000 RPM on slowing down. I have no codes and no engine lights. I cleaned the IACV and reinstalled but the problem came back relatively soon.

I saw one article on here about a teardown of the unit, but I can't seem to find it again. I searched for the past 30 minutes.

So my question is does anyone know what actually causes it to trigger an engine code or light? I highly doubt there is a "end of stroke" switch in either direction which tells the system it's actually open or closed. So if the unit is shorted or circuit is open, ok, I can see how it throws an error. If it's stuck one way or the other and the system recognizes car is running rich or lean, ok. But if the thing is just not swinging open 1/500 times when decelerating and causing a stall - it seems like this could elude the check engine light!

Anyone care to provide their 2 cents.

I'm going to swap the part with a URO aftermarket piece. Might not last 200k miles, but should be good enough to know - even if it lasts a year.

High speed, no issues. Only on off throttle, when decelerating. Never misfires at idle (once it's idling). I've swapped many sensors, and some of them more than once. Swapped fuel pump and MAF.

Thanks.