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IAC Valve


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Hey Guys!

 

A while back when I was on GMForums.com, a w-body member there suggested I clean the TB on my mom's 3.1 with some intake cleaner and a toothbrush, and to clean the IAC (Idle Air Control?). Now, I'm not sure what it looks like, but I assume its inside the throttle body? Does anyone have a pic of this?

 

I think the guy might be on this board too.....Canadian Badass was his name on GMF.

 

Thanks alot!

Owen

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I don't have a pic , but it is on the T/B. If it's a 3.1 you working on , the iac valve will be located on the front of the T/B if your stanind in front of the car looking at it. It has 4 torx screws on it and an electrical connector on it (if I recall correctly) , and when you pull it out, it's got a conical shaped plug on it with a spring behind that plug. Use some throttle body cleaner on it.

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There's only 2 torx screws holding it on. Be careful not to push the pintle in on it, you can goof the motor up inside (strip it out). Clean around the pintle and inside the throttle housing. Don't get any cleaner in the electrical parts.

 

Real easy to do, good luck!

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When you remove the IAC valve, make sure you squirt some carb/throttle body cleaner inside where there IAC valve came out.

 

Squirting some carb/throttle body cleaner in there does not clean it thoroughly. You need some blue towel or any lint free cloth and clean the inside where the IAC valve goes in. You have to use your index finger or pinky to reach that area since it will have some gunk in there.

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Why not just remove both parts?

[Remove the 3" rubber air tube to the Throttle body]

 

I removed the bigger flat cover piece first, the one the little black hoses go in, cleaned thoses passages. All the cleaner runs down into the throttle body and out the front. I held the throttle plate open to let it run out easier. Then removed and cleaned the IAC itself.

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So is the IAC the one that goes into the TB horizontally, and has a hump cast into the top of the TB for it to go into? There's two torx screws holding it in, and a 4 pin weatherpak connector.

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Yes, that is the IAC.

 

It's a solenoid that opens and closes a passageway for air.

 

I just have one tip, if you remove it from the car to clean it, make sure you dont push in or pull out the arm, internal damage can occur if you do.

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Hey!

 

Ok, I found the IAC valve, and I removed it, cleaned it, cleaned the TB, and the hole for the IAC and so on and so forth. Just have to get the intake back on.

 

Thanks for the tip. I didn't move the plunger though, because I didn't know if it would do harm or not. I also figgured that the connector was supposed to move the plunger. NOT me.

 

I'll let you all know how it turns out when I get it back together and go for a drive.

 

Thanks alot everyone for your help!

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Well, I'm having problems. It seems maybe the IAC is sticking.

 

At first, while the engine was cold, the RPMs would hold at 1500, then suddenly drop to about 600-700 RPM. I drove around for a while, and as the engine warmed up it seemed to go away. Now when pulling to a stop the RPMS are at about 1000 and then drop again to 600-700 RPM, but the idle seems a bit low and flucuates slightly. The oil pressure fluctuates also, and is almost in the red at idle.

 

Is this normal? Or did I just uncover more problems?? The car only has 179,000 KMS, but I did clean a fair amount of carbon out of the TB and the port for the IAC.

 

I read somewhere about someone following an Idle Re-Learn Proceedure....do I need to preform this?

 

I'll let the engine cool and then check the plugs. Might also be the fuel filter.

 

This sux.

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You would want to wait a day or to for that "relearn" , but with everything you have descibed , it might be the tps sensor...... "also on the throttlebody. You would need a digital multi meter to check it though....

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Gas line A/F is actually methanol or isopropanol (2 different alcohols).

 

It's molecules absorb any trace of moisture that is in your gasoline.

 

Don't use too much or it will affect any rubber components in your fuel system.

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  • 2 weeks later...

Well We've been driving the car for a while now, and there aren't any sharp drops in RPM anymore. So the IAC sorted itself out, and after cleaning the IAC and TB I think I can feel it pulling a little harder, but I don't know for sure.

 

It still seems to idle kinda rough, and the oil pressure seems a bit low while idling. I should change the plugs and fuel filter, maybe that'll help the idle out.

 

As for the oil pressure, is there maybe something wrong with the pump? Whats the normal "hot" oil pressure supposed to be for a (series 1?) 3.1? I can't see the bearings being in too bad of shape. The P/O was an old guy, and only put 170,000 KMS on the car. Maybe he never changed the oil. lol!

 

Thanks guys!

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