Well I just got my LT1 together, and fire it up, but it idles at 1800 or so RPM. I checked for vacuum leaks in the manifold/throttle body with carb cleaner, nothing. IAC is within limits. TPS is ok. Idle screw lets the throttle body close and throttle linkage isnt binding. What else could it be?

I gotta be in FL by Sunday, so I gotta get this thing running ASAP.

 

After I cleaned my TB, the rpms would hand. I badded some oil on the butterfly rod where the rod enters the housing and fixed the issue. It's worth a try.

 

I forgot to mention, I tried the idle relearn procedure, and no go.

 

I guess I need a scanner, anyone know where I can pick non-mailorder? I've only got a few days here.

 

Is it true that the IAC will retract all the way when the key is turned to on?

 

In the process of buying an OBDI PCM for my conversion I ended up with two
bad PCMs. One of the bad PCMs had a high idle, with everything else OK. I
have no idea why, it was just bad. After installing a good PCM, the idle was
just fine.

 

How did you know it was bad? Can a dealer test it if its just a high idle?

 

try the spart plugs... Thats what caused my idle problem

 

Spark plugs? Wouldn't that cause a low/rough idle if they were fouled? Besides they are brand new with the MSD ignition.

 

Ive got similar issues Im dealing with.
RPMs=1475
IAC=97-101
TPS=.56v@0%
PCM RPM request=900
TB is a Holley twin 58mm.
I also have no vacuume leaks. It seems to do this at least once a day, but after I shut it off and restart, it's fine. I just cleaned the TB and lubed the linkages to eliminate posibilities. Any suggestions? Sorry to hijack.

 

The only reason I knew is because everything else was fine. With the OBDII
PCM idle was fine. I plugged in the OBDI PCM and the idle was 1,800. Did
the reverse and idle was fine. Got another OBDI PCM and the idle was fine.

 

No, the more info here the more suggestions can be made. I think I'll take the PCM to a dealer tmw to see if its still good. Other than that I'm out of ideas. Guess I'll have to put it in a shop.

 

Try to find someone with a similar car and swap PCMs. At least you will
eliminate one possibility.

 

Anyone is central NJ with a 94 LT1 M6? I'll probably have to take the PCM to a dealer.

 

Fixed. I completely disassembled the throttle body and put it back together to double check myself. Didn't work. So I figured, what the hey, lets put the IAC from the V6 on there and see what happens. Calms right down to 800. Maybe the worm gear was bad? Both terminals were reading ~50 ohms when I tested it, but I guess it was still bad.