Sticky IAC After Bin write

[Muncie]

HI lads

Bit of an odd one for you to think about ive had IAC issues forever on my car and found it has a larger than normal Pintle and bore so any replacement i fitted just fell apart as it was driving into an oversized bore.

I found the correct size Pintle on a US spec IAC, socket was unusable as it faces the throttle body but after swapping the Pintle on to an Ozzie spec driver it works perfectly.

What ive found though after a full .bin write it sticks and idles at 2500rpm I need to undo the screws on IAC and it comes back online pulls back the hi idle and I can tighten screws an its happy again.

Cal write is fine and starts normally otherwise. Is my IAC Park position wrong or something else?

[immortality]

There are 2 different size pintles used on Commodore TB's. Somewhere around the VX they went to the larger size. This is assuming you are still using the factory style V6 TB?

[Muncie]

Stock vy throttle body, hasn't been modified or anything. Original failed years ago I binned it and fitted a new one that played up constantly. So im on 4th one all up, sticking valve is new

[immortality]

Bugger.

My understanding is the IAC resets itself on every key on cycle unlike the earlier 3800 V6 motors that required the idle learn procedure.

I have had the high idle issue before but that was the TPS reading wrong because the butterfly stop wasn't adjusted correctly (on a bored out TB).

[antus]

Its wierd that you have odd size pintles on a standard TB. Normally high idle is air leak and I've seen that with mis-matched IACs where the pintle is too small or doesn't extend far enough. But then you say its ok after removing it. What does the IAC steps in the log say? if you cant adjust the throttle stop and get it to sit at about 30 then the IAC doesnt fit properly or you have some other air leak. Could it be a problem with the seal and after a while an airleak forms and re-seating the IAC plugs it again, for a while?

[Muncie]

Sits normally in 25-30 step range. Can hear it run key on...... I may need to order yet another one now i know there is different sizes.

In the interim first start will plug in a spare iac after a flash as it only plays up during first start with a new BIN. Will have a look at valve park settings too.

Current fault finding has been polishing the Pintle so it is less easily trapped if that was the problem and also cleaned up the thread the Pintle runs on too as it actually wasnt manufactured that nice bit of fine filing tidied that up added fresh lithium grease. Deburred seat in throttle body as that also wasnt great, given everything a good clean has made the unit quiter so mechanically at least its better than it was.

Seems to drive closed and sticks (low idle or no start) or pulls back to far and give a high idle.

[kur4o]

There is install length on some vehicles, measured from base to top of pintle. If that is not correct you can experience different issues, sticking or not closing.

Check service manual or start experimenting until you get correct operation.