There is 4 bolts to remove to take off the throttle body. You'll have to disconnect the throttle cables, hoses and sensors too.

The IAC is on the bottom of the throttle body. If you look into the TB you'll see the small hole in the middle of the barrels, this is where the air goes into the IAC.

The IAC is removed by removing the Torx screws in the bottom, you might have to replace the gasket. After a while the rubber gasket get's distorted and using the old one, just doesn't cut it. Which brings something else to mind, maybe the gasket IS distorted, that could cause a problem.

Anyhow disassemble the IAC, clean with the carb cleaner, the spray a few shots of WD-40, P'Blaster or something equivalent that will lubricate the "motor".

Then re-assemble.

As far as checking for vacuum leaks, take that same can of carb cleaner and spray the engine in the spots of hose connections, near the intake's bottom. While the engine is running of course and do the IAC cleaning part first.

If any leaks are present, your motor will REV up because the leak will suck in the cleaner.

Now I see a problem with checking it this way just because of the accused IAC problem. the IAC will probly be bouncing the IDLE up and down, so it'll make it much harder to diagnose a vacuum leak. So I'd say try to clean the IAC so it stops sticking in the open position, then check for leaks. And triple check a spot if you think it's leaking.

Are you leaking any oil down the backside of your engine on the driver's side? Thats a popular intake leak on the LT1s, so you might wanna check that also.

I hope I was helpful.

 

That sucks you paid that I got a tech 2 scanner and I only live a fe miles from orlando

 

ok i had that same problem . . . well this is how i fixed it


i chanded the wires and plugs and upgraded my ingnition to an accel 300+ with the coil . . and after that my car runs perfect and up in the rpms my car feels so much stronger . . .no miss or nothing i suggest you follow what i did you wont regret it and im shure thats what the problem is . . .

 

Well, let's do the cheapest way possible first. Here are the possibilities, ranked from cheapest to the most expensive:

1. IAC Sticking
2. Intake Leak
3. Non-Vented Opti-Spark

But it's your time and money! Just a suggestion.

 

Does the problem go away after its warmed up?

On cold start up, auto's idle high like that. Let it get up to temperature and if it starts idling around 600-800 rpm, then its fine. If not, then its probably the IAC.

 

How much of an effect does the infamous intake leak have on idle?

 

thank you very much for all the help.. sideways..how much did all that replacing cost you? and I really dont want to mess with the engine removing parts like that,, how much will it cost me to get the dealership do all that for me.. or better yet just change the IAC? thanks again guys

 

anybody in here from chicago or central IL that can help me?

 

I had the same problem with my Z a few years ago. I finally tracked it down to my bad EGR valve, I just decided to remove the entire EGR system and I have not had a problem since.

Derek

 

where is the egr valve and how do i replace it?

 

welcome to the club. It was actually a 1500 mile trip to the lovely sugar bowl that we lost. Im hopefully gonna get it fixed tomorrow. I will keep you posted. Its driving me nuts, but i am pretty paranoid. I have a damn backfire now during slight acceleration and worse hesitation. Its not the opti, so everyone quit saying that ****. Otherwise the cars would do it when they are cold which they do not. I am sitting at 83k on the odo, I changed the opti not 4k ago. I know the symptoms of that and these arent it. It wasnt the iac for me. I took the bastage out and cleaned it better than new, same with the throttle body. I bought some 3m intake cleaner thing which im gonna use this weekend, it requires some special nozzle or somtin. I wouldnt necessarily say that cleaning the Iac did anything. I am completely stumped, so hopefully the shop can figure out what the hell is wrong with this thing. Ls1 is looking mighty nice now. ha ha just kidding. -Michael

 

Tell ya this much it aint the EGR or the Opti. Rebuilt my motor and and removed the EGR and air pump. Also had a brand new OPTI. I had the problem awhile back for like a couple weeks and it wasnt after a long trip or anything. I recently removed some excess air lines and sensors ( i think they're sensors). SInce then I haven't had any problems.

 

please keep me posted on whats going on.. thanks

 

SJS, can you be more specific? I am thinking of egr and air is all that you can remove.

The egr really seems suspect to me, since it has happened to a few people after long trips.

 

Did anyone get codes for this? Derek 94z28 were u getting a code when it was your egr. I didnt get my car to the shop, because i overslept. I am gonna take it to my buddies long time garage tomorrow since he knows the buy personally. I am gonna solve this $hit!!!!!!!!!!!