I can't find this part on the Scottsdale web site. Does anyone know what it's called or how much it costs? I need to get mine replaced ('92 Q) and I want a guestimate of how much it will cost (incl. labor).

Byron at T-3 has my idle turned all the way up and said it won't go any higher. I replaced the MAF but the idle still dips to around 600 rpm at times and it causes the car to stumble on initial acceleration.

Hoping it's cheap and easy.....

You mean the AAC valve? (My '91 FSM doesn't show an IACV) (Auxiliary Air Control)

Here's one from rockauto.com (They call it an IACV as well)

http://www.rockauto.com/catalo...=2881
Modified by anlasak at 8:53 PM 9/26/2005

Personally id try and find one used. Get one from mark86t, the Q he was parting out had a shot engine.. I bet hed give you one for under $30

While we're on this subject, what does the IAC valve do?

I know it controls the idle speed on deceleration etc. but does it have anything to do with compensating Idle Speed when the A/C compressor is turned on?

My car idles fine, but when the A/C is on it drops maybe 150RPMs. I checked voltage, got 12vdc at the plug. It didn't do this before the Plenum/KS Job...

What "senses" the A/C compressor? The ECM?

In my '91 FSM, pin#58 off the ECU controls the A/C Relay, which in turn controls the A/C compressor.

It has always been my understanding that the ecu has a pre-set base idle and when you turn on the A/C more load is placed on the engine,lowering RPM's. This in turn causes the ECU to actuate the IACV/AAC, allowing more air in to compensate for the additional load placed on the engine,(ie, raising RPM's back up to base idle).

Not that I'm right, just my thoughts on the matter.
Modified by anlasak at 12:12 PM 9/27/2005

The IAC should compensate when the AC turns on, but Ive found that most Qs it doesnt do this for whatever reason..

That may be due to the fact that on most Q's the base idle has been set higher to cover up vibrations...

There are several inputs for the AAC valve opening besides A/C use.... P/S load, Alternator Load, etc.

Heath

So the part is around $300? I don't mind buying new parts but I was hoping I could stretch it to the next oil change.... but cars is acting weird about once or twice day. Might as well whip out the plastic and do it.

Is there anything else that should be checked and/or cleaned at the same time? Throttle body was cleaned in May; MAF, fuel pump, and FPCU are new.

I'm at the fix-one-thing-and-something-else-breaks stage right now and I'd like to get out of that routine.

Before I'd buy a new one I'd check the one I have over thoroughly.

If the mechanical components are cleaned and work properly, I would start looking at the electrical compoents.

But if thats not something for you, then I would take Elwesso's suggestion and see if anyone has an extra laying around for cheap.

I just finished my KS/Plenum job also.....

When I found out the part was $300 bucks!!!, I unplugged the IAC, turned Ignition "ON", checked for 12vdc @ the plug. (OK) I was too lazy to "ohm" out the Selinoid so I plugged it back in. Then I turned the adjustment all the way "IN", then backed it out 3.5 turns. (I count in 1/2 turns which is 7) I've read that the range is 2.5-3.5 turns out. At 3.5 the idle seemed a little high (warm), so the next morning I turned the adjustment screw in 1 full turn, went for a drive and it was better, but still a little off. I gave it a half turn IN yesterday, didn't get to leave the house, but in the driveway I noticed when I turned the A/C off, the idle stayed the same...Going for a drive today to see what happens...

I found my exhaust leak comming from under the heat shield on the drivers side Cat. That Seafoam sure is good for finding exhaust leaks...Checked the price of a Cat? Now thats an eye opener....:-)

Seems the last adjustment did the trick...the Tach is much more stable when the A/C is switched on...maybe a drop of 25rpm...much better than it was...

Pulled the heat shield/sink on the Cat. and found one leak at the weld...but I have another one on that pipe closer to the manifold...Jeezee......

Hey Wes, do Ya think I cracked the EGR tube by moving it slightly during the Plenum job? I can't see anything wrong with the tube...I guess I'll have to Seafoam the thing again to find the second leak...