ls1 "vacuum leak" help

[Mattp427]

Hey guys, ive got a 99 trans am and when i bought the car the previous owner gave me an ls2 intake with a larger throttle body and i could never get it to idle because it was a cheap throttle body and it would read the throttle position at 29% with the blade closed and after i bought a name brand throttle body it started idleing at like 2 grand and the kpa was only at around 29 so i figured the intake must have been cracked somewhere so i just swapped the stock stuff back on and now its idleing at 3k rps, ive made sure the gaskets were still pliable and should be sealing, it sounds like there is a leak but its coming from inside the throttle body or like the intake because with the airlid on i can put my ear to the front of it and it sounds like theres a vacuum leak, if someone has a stock tune file so i can compare mine to it that would be awesome, or if they know that i am doing something wrong im positive that all vacuum lines are hooked up and that the intake is torqued to spec, any help would be greatly appreciated because i have tried everything that i know what to do.

[Xeen1901]

Do you have a log of it running?

[Mattp427]

stupid high idle.hpl Here it is

[Mattp427]

Okay so with several tests, what I am thinking is that something is going on with the iac, we have replaced the iac, and no change so something must be going on with either the tuning side or the wiring side. How I have come to this conclusion is that with the intake hose off the throttle body I can put my finger over the hole where the iac is supposed to operate and can idle the car where I want it, so that is where I think my "vacuum leak" is coming from

[GHuggins]

Have you checked your tps voltage? It's what more or less controls the idle air controller outputs. May be a bad sensor or maybe just needs adjusting?

[Mattp427]

im showing 0% of tps on the scanner

[Xeen1901]

I would check actual voltage at sensor signal wire, not just by the scanner. Have you tried blocking off the throttle body and starting it? Could make it easier to find the leak if there is one.

[carolinarodshop]

Smoke test for vacuum leaks. Was the tune ever modified for the LS2 throttle body and injectors? Try logging the IAC counts and TPS voltage.

[Mattp427]

did a smoke test, found no vacuum leaks, smoke was only coming from the air lid, so i pulled out the iac and could see that the pintle was retracted into the iac and that it was letting air go past it, so i found that you can manually adjust it and pulled out about an inch reinstalled it and the car idles, and then the rps just start to climb util it gets to around 2500 to 3000 rpms, so i pulled it back off and its retracted all the way back in again, so what tells the iac to close and what can i do to keep it from closing and not doing its job

[Mattp427]

Attachment 65629 this is with this tune Trans Am #1.hpt and its pretty much what i have started with, ive made small changes but it hasnt really improved anything.

[Mattp427]

high idle.hpl

[whistler777]

99 stock.hpt

[MMGT1]

Pull the IAC Motor. The Pintle cannot extend more than 28mm from the motor. Disconnect power from it when you do this(I would also unplug the TPS so it can be reset as well). With IAC and TPS unplugged go to key on. Key off and plug in IAC and TPS. Key on for 10sec and off for three 3 times. Start engine on third. Scan for IAC in your run. IAC should read 0 at around 50kph or so. Find a stretch that you can run a few mins at that speed. Turn around and do it again. This should allow your IAC to learn its position in your throttlebody. Key here is you cannot just move that pintle, the measurement is real bud...it must be around 28mm at time of instilation or it will not function as designed.

[wasyl]

to my mind MAP is fine, it just runs to lean, with MAF that high

best regards