confused?!?!?
 

i called the dealer to get a labor quote on getting the idle air control valve replaced. he said the main one is $175, the auxilliary one is $195. huh? "there's two?" "THAT'S WHAT THE BOOK SAYS"

what's the deal with the IAC valve(s)?

^bump^

NOBODY has ever had the IAC valve replaced???

There's probably no reason to replace the IAC. Normally they only need cleaning (unless you drive a Ford.)

thanks Beav. are there two of them, though? (main and auxiliary)

There's only one that I can think of:

http://www.subaruparts.com/diag/?mod...ategory=063-A2

See: #2

Unless someone is confusing the IRIS valve for something it isn't.

Auxilliary air control valve
 

Here is the other one. http://www.subaruparts.com/diag/?mod...category=036-A

I have no idea what this does, as it is powered by 12 volts at all times and has no control signals whatsoever other than it shuts down when the fuel pump relay shuts down. I pulled mine off to check its operation using battery power. Seems to do nothing. I'm thinking about leaving it off the engine to see if it does anything, just bypassing it with a hose, as it always seems to be open. Maybe when it is hot it closes more? I'm confused too.

There are in fact two air control valves, the IAC (which controls the idle speed), and the Auxiliary Air Control Valve, which is used only to allow extra air to bypass the throttle plates when the engine is started from cold.

That valve is indeed controlled by the fuel pump relay, so that whenever the engine is running, 12V is supplied to the valve. Inside the valve is a bimetallic strip, which allows the valve to open when cold, and gradually close when 12V is applied, and the valve warms up.

If the valve is cold, it should only take a few minutes after 12V is applied for the valve to close completely.

Jason.

Thanks
 

Now that makes sense to me. Thank you for the clairification. I guess the only way to test the operation is to not only apply the voltage, but also to heat the valve.

Thanks

one more question
 

Any idea which side the positive feed goes to for this application? It would be the blue wire. My clip came apart when removing it, and I'm not sure which goes to which side. Blue to the center of the motor, or to the driver's side?

Thanks

Chuck D.

No. What Jason has described so well, is exactly correct. The valve is in effect a thermal delayed operate device. Applying the voltage heats the element which then responds but only after a set period. Engine heat may ultimately assist, but is not the primary signal.

Great. I'll give that a try then. See if it closes after being charged for a while. Thanks. Any ideas which side is charged and which is ground?

I gather that the ground is within the loom and can not be easily identified visually. Check both terminals on the loom connector for voltage, using the engine as a ground. With the ignition on one should deliver 11 - 13 volts. The other will be ground. No volts detected and you have found a fault.

If you are energizing the unit on the bench, it will not matter one way or the other as it is not polarity sensitive.
Looking at an earlier post, it would appear that the connector may not be polarized and may go together either way, in which case have no concerns.

Polarity
 

Well, its just a matter of mixing up the sides, so if what you say is true, I should be able to connect the wires at either side and it won't matter as long as one is 12 V and the other grounding. I hope you are correct. Where did you get your info?

Thanks for your help.

Here's a lazy person's way of testing the aux air valve. I've found that when the engine is cold, you can blow through the Aux air valve. If you look in my locker at photo 11, you can see the inlet tube. You should pull the outlet tube off of the throttle body to feel the air going through the valve. After the engine warms up, the valve closes and you can't blow through it anymore.

testing
 

I was thinking of trying that. Problem is, I'm going to be tuning with Tec II and I don't want any more problems to creep in, other than the ones I'm going to be dealing with.