Bet most of you with some models of 22re's don't know there's a Hidden Thermostat (beside the one for the radiator) on your engine. And I'll bet there are quite a few members on this board that do. I didn't

I've been trying to hunt down a problem on my 95'4rnnr w a 22re for some time. The most bothersome one is a very mild constant fluctuation in RPM's at just about any speed. I can run the idle up and hold the pedal steady and you can see the tach just barely moving up and down. Sometimes I think I can feel it even when driving as a small acceleration/decceleration. Then there is/was the uneccesarily high cold idle . Like > 2500 RPM's

I checked the specs on fuel delivery- pump , pressure regulator etc. , MAF , TPS , and then cleaned out the throttle body, which was a litlle gummy but nothing bad and I decided to open up the Idle Air Control Valve and clean it.

This is where I discovered the hidden thermostat. The IACV on this model is controlled by coolant temp. This is where I also made a big screw up and didn't record the original position of the IACvalve seat before removing it to be cleaned. It's that part in the following pic with the slot on the side. Rotating this seat CCW loosens it and allows more air flow through the throttle body at cold temps thus increasing rpms.



So, I cleaned it all up, put it back together - putting the seat where I thought it should go from memory - and put it on the vehicle and now even with the idle adj. screw all the way in it's running like 1700 RPM's when warm.

So I take it back off and apart and adjust the seat down a full turn and try it again and it's a little better but I figure I'm going to end up taking this thing on and off 50 x's to get it right (even though I can do this in ten minutes by now).

Looking through th FSM I couln't find any reference to an idle down temp so I decided that 170?would be a good place for the IACV to shut off extra idle air so I set up the following contraption to adjust the seat at that temp.
Just pressurized a tank of water at 170? and ran it through the valve for a bit then adjustted the seat closed.






High idle when cold seems to now be adjusted pretty close to where it should be , around 1700 RPM, and the engine idle when warm is more stable now . My idle adjustment screw on the throttle body is set about 5/8 of a turn open which seems a little tight but that's what it takes to get a 750 RPM idle. If I were to adjust the IACV seat out further -closing at a higher temp - more air flow- higher cold idle- I would end up screwing in the throttle body idle adj. screw in even more to get the warm idle back down. All this and the mild RPM fluctuation is still there though.

Any how , sorry for the long post , but I know others have little hair left too after troublecrapshooting idle issues on these motors and thought maybe it would spark off some ideas.

I'm thinking as the IACV ages , the range of motion in the thermo valve probably begins to decrease or get sticky and this could be why over time we keep having to adjust our idle screws in more and more over time.

Sheesh! Tell me about it. I had my own tussle with the IAC valve. http://www.4x4wire.com/forums/showf...;amp;page=0&fpart=3&vc=1

It's interesting to know that you can control the idle setting with how you set the IAC. Didn't know that.

Definitely archival stuff. Interesting how you rigged that up.

There's a pretty good tech article on autoshop101, idle air controls for a good read too.

You know... I wonder... if you were to go to a local Toy dealership, and ask to see a matching IAC valve, if you could compare the location of the stat in that one with what you had.
The logic being that it is probably set at "stock" from factory.

I thought about "borrowing" one also but it is a special order item.

Maybe the next person to buy one can post some measurements.

1- cover surface to valve tip at 32? (run ice water through it)

2- cover surface to top surface of seat.

3- temp at which valve closes.

Great information! I am currently battling a high idle after a TB swap and had the IACV off yesterday trying to figure out how to unscrew the spring, it fought like hell so I decided to give up and track my problems down elsewhere. I see the tool you made there out of a socket,I am going to have to copy that idea and see if I can't get mine running right.

For future reference, please record the precise # of turns it takes to remove the valve seat.

Thanks

I ordered a new (used) late model throttle body with IACV from Yoda Jim's today. I am going to pull the IACV and install it on my existing TB to see where that gets me. While I have the old one apart I am going to see if I can get it within spec.
One thing I noticed when I found your post is your lock ring is screwed in way more than the one I have in the truck now. From memory the top of the ring is sitting pretty much flush with the threads. Also my thermostat unit was sitting much further in but that is probably due to it being cold and not yet expanded.

Good eve!

Not wanting/trying to hijack, I have a prob w/'89 22re that wants to sputter out the exhaust @ idle. It has 320k. My local toy stealership wrench said that usually happens if iacv is clogged w/carbon/sludge etc. and is "sticky" and does not work correctly. Not sure if yours is having similar issues. Have had no luck getting the four screws broke loose yet to get it apart to clean. Any similarites?

I have been noticing a miss at idle, but I am not sure if it has anything to do with the iacv in my case.