I've been getting a low idle on my 95 lt1. Now I cleaned the Iac prior to the first start of my engine, and it was pretty clean already.

DRIVING:
When starting the engine, it runs fine. Idles at about 700rpm. When I drive and i hit my clutch in it drops low fast, and when i finally stop it sits at about 400-500 RPM. Not rough, but just low and struggling to stay fired up. It does that for about 5-10 seconds of being stopped and then idles fine again around 700rpm. It does this about every time.

Now I notice those symptoms somewhat go away when the engine is really warmed up, and a hot day seems to help it idle better coming to stops.

INSPECTION:
I didnt think of IAc since I checked it but decided to look at it anyway.
I ohm tested it and when touching the two outer connectors, I get around 50 ohms. What is the correct ohm? Also I plugged it in and turned keys to "on". I guess it is supposed to move but after 10 tries, I saw no movement. I moved the Pintle in and out. Actually it came all the way out. Is that supposed to screw in or pop in?

Anyway hooked it all back up, started car. High rpms (1600rpm). settled back down to 700 after a moment. I thought it was fixed cause the idle would come down much slower than before and never dropped low. The real test would be when I drove it from cold start... which I did later the night and the symptoms seemed to return.

The idle isnt horrible but all my tests seem to point to bad IAC, and I hate to buy one, not see a difference in idle and not be able to return the part because its an electronic item.
ANY HELP?

 

Well you are not supposed to push them in and out unless they are brand new and you have to adjust the height, so if you didnt need one before, you may need one now I have been looking into the IAC becuase I have a high idle (~1000rpm) issue that I cannot figure out (no it isnt a vacuum leak) and unless you have the Tech 1 and can command the IAC in and out and measure the expected resulting rpm, I dont think there is anyway to definitively troubleshoot the IAC. I think you pretty much have to use process of elimination, though I will be interested to see if anyone else has any ideas.

I plan to just buy one, keep it clean and try it out, if it doesnt fix the problem, I am going to try to return and just say I got the wrong part. My local autozone is usually pretty good about that.

 

Well if moving it in and out wasnt good... it's not any worse than before. It's in the same condition as before. I thought maybe the pintle was stuck so I wanted to break it free of any gunk. Any one know the correct ohms or to confirm that the pintle should have some movement on the turn of the key to "on"?

 

You can check the resistance all day long and you usually will never find any open windings. A few ohms more or less will not matter. It will probably move if you pull and push it but all if this means nothing. When they go bad they will just not respond to commands and step properly.

I have replaced many on different kinds of vehicles and none of them checked bad. Just replace it and don’t over analyze the symptom. It usually fixes it and if it does not, you have removed a big variable in the equation. You then can continue to troubleshoot.

 

I have looked at various brands that vary from $40 to $100.... any advice on that. Higher price = higher reliability ? or they all the same

 

I usually go to my AC Delco shop for critical parts like this.

Don't forget to clean the bore in the IAC housing before installing the new unit.

There should be a spec sheet with the new unit that specifies the correct pintle lentgh before installing in the bore.

If you had a scan tool you could see what idle the ECM is calling for when cruizing and you push in the clutch.

 

The IAC coils should measure 50 to 55 ohms.

The dimension you see in various places is the MAXIMUM length to prevent damage when the IAC is installed. You don't need to set the pintle to any special length. Just push or screw it all the way in with your fingers. The ECM will set it correctly when you cycle the ignition on/off. The important thing to watch for is to not have the pintle too far out when you screw it into the throttle body. It can break. Been there. Done that.

 

My friends 97 is doing something similar. He changed the IAC, it did not fix it.
I read on here that over oiling the K&N filter could coat the MAF burnoff wire. He cleaned that & it helped, but the condition returned.
I say since it helped he's on the right path. He say's it didn't fix it so I'm wrong. Whatever.
Just try cleaning it & the MAF screen. It only takes a minuet & some MAF cleaner.