Rjmco

Let me first say that this forum has in the past been a great deal of help to me (even though I have just been lurking)...so thank you in advance.

I have a 91 pickup w/the 22re. It has the surging idle that seems to be pretty common on these things. That said, in the past, I've been successfully able to remedy the situation when this happens. Right now, unfortunately, I am a bit stumped and hoping someone will have some suggestions.

I have replaced the thermostat. The line from the thermostat housing through the IACV is clear. If I put a little air pressure on the input (to the IACV) hose, I can see the fluid returning to bowl under the thermostat. I took the throttle body off, and cleaned the butterfly, as well as the removed the IACV itself and thoroughly cleaned it. I know the thermostat works, because I boiled it. I also heated the IACV while it was off and could see that it did in fact operate as it should. The idle set screw is completely screwed in...i.e. the idle is not set too high as is sometimes the case.

Everything is back on the engine...idle is atrocious. If I take my propane torch and heat the IACV the idle will eventually smooth out. So, I am making the assumption therefore that the IACV is functioning. I'm not certain if it's possible that it is "working" but due to age, etc. it is requiring a higher temperature than the coolant can provide. I know my torch is a lot hotter than the coolant. So maybe that's option 1....IACV defective? I am convinced the idle is related to the IACV (and not other air passing through the intake) because when the IACV is heated, idle is just fine -- maybe I'm off base on that, but the logic seemed reasonable.

Option 2, is that for some unknown reason to me, the coolant is not making it's way to the IACV. To be honest, the feeder hose does not ever seem to get very hot to the touch. The engine is not overheating, and other than idle seems to be running fine. That hose and the IACV passage are of fairly decent size, so I have a hard time thinking they're clogging (plus I can see they're not as mentioned above). I have checked the radiator and fluid overflow...they are appropriately filled. The water pump is only a few years old and has less than 30k miles on it...and again, since the engine isn't overheating, I have a hard time thinking it's related to the pump.

Any thoughts? I know this is a pretty common issue and I've read a bunch of posts...and that is what has got me to here.

Appreciate any advice you can give.

Thanks!

Thommo Thompson

are you adamant that the smoothing out of the idle is definately a result of heating up the Auxiliary Air Valve? (thats what its called)
Not just coincidence that its smoothing out as it gets in to closed loop mode?
If you're certain, (done many tests with engine both hot and cold) then that cool line going to the valve body is a concern.
An air bubble can do this, air wants to rise, so if the air bubble is big enough, and the line is thin enough, the air bubble can stick together and push up and airlock that part of the system, and the coolant just takes the path of least resistance and bypasses the circuit all together.
Might be a god idea to undo the coolant hose (FROM) the throttle body,, on the from side, as the coolant comes out of the body, and run the engine and give it some revs so it tries to push coolant out the open hose, then stick the hose back on while its flowing.