Thread: Possible o2 Problem, Need Some Confirmation

I'm going to have to hook up my PT and scan. My Aeroforce gives IAC in different units and it doesn't have the VAC value.

I haven't seen idle LTFTs that high before, but I haven't been paying attention at idle either. Also, if its just one injector o-ring my PCM might not even be away of the problem. More investigation is needed.

How do you use carb cleaner to locate a vacuum leak?

Originally Posted by TDCRacing

spray the carb cleaner around all the gaskets that you suspect may be leaking.when the car is running and you do this you will hear the motor rev up a little.

The plot thickens.

I went spraying everything vacuum related listening for a change. I sprayed the IAC and I heard the exhaust note change just a little, then go back to normal. It was hard to hear over the engine bay noise, so I aimed at the IAC, put my head around behind the hood and did it again and there's a definite change. It's subtle, but the sound of the exhaust does change slightly (like a extremely slight rev) when I spray it.

It might make sense because I've had the IAC out a few times over the years and never replace the gasket or anything. Never followed torque specs either. I'm about to go get some tools and see what I can find.

If it is the IAC, then it's been like this for a while. Could it be so simple... I made sure to give the lower injector o-rings a good amount and never noticed a change, but I may go back since I know what to listen for. Grabbing the tools and heading downstairs now...

That orange o-ring. Is the factory IAC supposed to have one? Mine... doesn't.

When I took it off, the very bottom (outside) edge of the IAC on the flat section has some thin carbon buildup all along it that fades as you get close to the IAC opening. It's definitely been pulling some air in from around it for some time. Also, there's carbon build up in the initial bore for the IAC to slip in to. I may have just found at least part of my issue.

I put it back on and tightened the screws as much as I felt comfortable with and started it up. Initial surge on startup seemed less and the engine seemed "smoother". But, I'm guessing I need that o-ring...

Yeah, you need that O-ring. If you have an Oreillys near by ask them to see there o-ring assortment behind the counter. They should have a whole tray of o-rings (ask someone thats been there awhile, not some new guy. They will try and take you to the Help isle), match it up. If worse comes to worse HELP makes a box of orings, there MAYBE one your size in there, not sure though. Either way, get an o-ring....

If I can't find one, I'll just buy a new IAC. First I'll try Oreilly's, then I'll hit up my parts guy at the dealership and see if he can order just that (he gets me employee pricing ), otherwise I'll compare his price on the IAC to RockAuto's.

Scotty, if you're reading this, it may explain the slight dirt ingestion that came up in my analysis.