While in P or N, at stop, my idle undulates from 1500-2000 rpms, only when warm. I am thinking vacuum leak, but I cant find it? Is it possible for the metal gasket on the heads to the LIM to go bad? Mine is not rusted, just some of the black paint flaked off. Any ideas?

 

I have a high idle when the temp. gets cold, I don't have any intake leaks to my knowledge and I have still never been able to figure it out. But as far as the LIM gaskets they are crush gaskets so after you use them once the ridge is gone, so yes it is possible to have a leak there if you re used them. have you tried using some carb/choke cleaner to find a possible vac leak?

 

Maybe this is your problem...? You might not have got it sealed 100% as you thought like you said in your Macgyver thread.

 

As said about 4 times in my thread, I fixed that today. Geeze people read. (no personal offense, it just seems it has been going on a lot lately)

Cardana, how high is yours when cold? On a cold start mine is atleast 1200, then works its way to 1500 then jumps up and down.

 

on start up its fine, around 1200 or so. But when the engine gets up to temp and has been run for (just a guess) more than 15 minutes the idle will creep up to around 1800. My dyno's look fine and my track times (13.8 @100) back up the fact that my car does not have anything major wrong with it, but the high idle is annoying.

 

1500-2000 rpm idle? Jesus, mine idles at ~750! I vote leak, as you guessed.

 

I was told by a mechanic friend after I sent him a short video of the idle that yes, it was a leak. Any suggestions on finding it?

 

Start with spraying some soapy water around the area you just repaired. Then spray around other vacuum areas..

 

Spray carb cleaner around the area. When you hit the leak, your idle speed will jump.