I took my car to GM this morn and I think the mechanic must have had a big butt cause his head was 6' up it.

The car is giving codes. Rich, lean, est. The idle is still up and down. He said his computer could change the values it sent to the IAC so he increased it to 2000 and it went up but then he tried to decrease the iac and it would not come down. It has a brand new AC DELCO IAC in it. He kept saying that that was the prob but I kept telling him that the old one is doing the exact same thing.

I am not sure what the codes would be meaning. Does anybody have an idea what would cause them. I was thinking maybe the distributor module was gone again because some times it is 1550 RPM's and sometimes it is 2000RPM's. And then again....sometimes it works fine. Last time I had a prob like this it was the IAC and timing module... I think this car is cursed. Anyway so far it has cost me $200 and I am no further ahead.

I need all the help I can get

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91 Z28 Camaro
305 TPI
Flowmaster 3" exhaust
700R4 with 2000 Stall and shift kit
One sweet sounding system

 

Well, it could be the ecm, or wiring to the IAC, if it doesnt respond to idleing down, then there is a problem with one of 3 things.. IAC itself, wiring, or ECM.
Since your IAC is fairly new, I would suspect a wiring problem..

[This message has been edited by Kevin G (edited April 27, 2001).]

 

Did Mr. Excitement check the simple stuff?

False air? Coked or sticking throttle plates? Did he follow the IAC diagnostic procedure?

I think he assumes it is an IAC problem because it's idle ... but when you *** -U-ME...

Worth asking,

 

Just replied to your last post. He has a point, check the TB for dirty and sticking throttle blades, and make sure the TB is clean when you remove it. Make sure the cables to the TB are clean, unkinked, lubed and free. Check to make sure the TV cable is adjusted right, etc. I'd fix the codes first, some affect idle, but usually the obvious ones like MAF. Also, the computer is supposed to start a little high when it's cold and slowly drop down to idle, to help warm the engine. I'm not sure if ALL TPI engines do this, though. Don't forget to replace your vacuum hoses. Hope this helps.

 

I know what you are trying to say!!! I have checked all the easy stuff. I am going to try to set up the IAC again and see what happens. It is doing the same thing with the new one as it was withe the old one. I don't think some people are understanding though. I have taken it to GM and they can't fix it!!!! It is not just me!

I have checked for thottle plates binding, I have checked the pintle on the egr valve, carb cleaner all around intake and lines, new IAC as the old one is doing the same thing, I put a new computer in. The only thing I haven't checked is the timing module. The trick with the problem is it is INTERMITENT. Sometimes it is working fine and the IAC is moving like it should and some times the idle sticks at 1550RPM's and sometimes 2000RPM. 2000RPM's just happens to be the max that GM can manually adjust it to on their scanner. This just happened one day. It did not progress over time and even if it was the throttle plates, you would think they would have given me trouble before this time. I am going to go through the IAC setup process and see what happens. Thanks for all your help and I will keep you posted on my progress.

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91 Z28 Camaro
305 TPI
Flowmaster 3" exhaust
700R4 with 2000 Stall and shift kit
One sweet sounding system