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Discussion Starter #1
I'm having a problem with my high idle (around 1500 when warm). When I try to adjust my idle I disconnect my TPS and my idle goes up even higher (2000+). I've tightened my idles screw all the way. I can loosen it but my revs go higher still.

I checked for vacuum leaks but if I plug the hole in the TB to the IACV I can stall the engine, so I assume there are no leaks. Even when I rev the engine there is still a lot of air being sucked through that hole.

What could be the problem? Help me please.
 

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Sup Mod keeping the peace
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If your engine continues to idle real high after it's warmed up, check the air regulator unit. It's located on the passenger side of the engine, below the intake manifold, near the rear. There's a hose connecting to it. Pinch the hose when you are having the high idle condition. If the idle speed drops, there's a problem with the unit. Also check the electrical ground connections on the engine for looseness and oxydation.

Another thing to check for is an air intake leak somewhere along the intake plenum between the Air Flow Meter and the Throttle Valve. Check all the nuts for tightness that fasten the intake system to the engine.
 

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Discussion Starter #4
I'm not sure if I have this "Air Regulator". My truck is a 93 HB, 4 cylinder. It's not giving off any codes (55 - all clear). I am in Ontario.

The IACV was disconnected for a while. I've reconnected it but nothing changes. If I put my thumb lightly over the hole to the MAF sensor the idle slows down. I did notice when I unplug the TPS the idle does drop for a split second then goes way up.

I will check the electrical ground connections today.

Any other ideas?
 

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Sup Mod keeping the peace
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If the motor in your truck is a KA24E, then it might have a fast idle cam that's part of the TPS.
 

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Discussion Starter #6
I've checked the fast idle cam. When it's warm it seems to be adjusted properly. I took off the IACV yesterday and the plunger looks perfectly clean. When I apply 12 V to it nothing happens (no clicking etc). Also the I can't tell if the AAC valve has moved recently either. On the side two holes there is a fair bit of buildup but the middle one is pretty clean. Does this mean it hasn't been working.

I'm just worried my ECU might be f***ed. It's not giving me any error codes (even when IACV isn't plugged in!

I'm going to try and find a used IACV today, but I'm worried it might not fix my problem.
 
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