Thread: Possible o2 Problem, Need Some Confirmation

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...