Cammed_ta

Hey people, as stated above I've searched and searched all night and can not find a permanent cure for my car. It's idling anywhere from 1800-2200 depending on cold start or warmed up.

Yesterday evening I picked up a 98 trans am, crate ls1 from GM, ls6 intake and throttle body, comp vrx2 cam, long tubes, and built th400 tranny and transbrake. This is my first ls1 car, but I work on all of my own cars so I'm not full retard, just partial lol. I bought it knowing it had a high idle issue, but was told it was an 02 sensor problem, but there were brand new 02's and new extensions in the back of the car. I put the car up on the lift and put them in and cleared the codes, started it up and the idle did not change. So I've been searching and searching. I sprayed all around with carb cleaner for vacuum leaks, no luck. Clean the IAC and port. But there's one weird thing that I did notice, I pulled the TPS last night and looked at it, put it back in but left it unplugged, then the idle came down to 1000-1100 rpm, which I was happy with. I plugged the TPS back on, car stalled but came back up and stayed idling at 1000. Shut it off and started it back up and was still ok. Well it has a battery shutoff unde the hood and out of safety I shut it off last night before i closed the garage (OCD that maybe it would burn down lol) this morning I went back down to the shop and turned battery shutoff back on started the car and the idle came back up to 2200-2500. Is this because the battery was disconnected overnight? I didn't have time to let it sit and run had things to do with family. Now I have absolutely no idea if this car has been tuned as the guy I got it from had just got it traded in and had no interest in it. Is there anything else I should check for? Sorry for the long story but trying to fit in every detail. Any help is appreciated. Thanks in advance guys.

Fry_

It's not the best idea to disconnect the battery unless you have to on any fuel injected vehicle because then it has to through its idle relearn procedure. But I doubt thats your problem it may be you best bet to just take the car to a good tuner, not knowing if a cammed car is tuned and driving it anyway doesn't sound like a good idea.

Cammed_ta

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I'm probably going to have to take it and get it tuned you're right. Did go back down and start it a little bit ago idled high for about 30 seconds, I unplugged the TPS again and within 5 seconds the idle was back down to 1000. Does that mean a faulty TPS?..

Prorac1

iTrader: (4)

You stated in your first post that you cleared the codes. What codes were they, and did they come back? Eric L

Cammed_ta

Sorry I got a little carried away and skipped a couple things lol. The codes were for 02 sensors, I changed them, cleared the codes and they haven't came back. Other codes are for transmission but that's just because it's got a turbo 400.

Cammed_ta

Another thing I'm curious of. It's throwing all kinds of transmission codes because of it having a th400 in it, and was a factory auto car. Would this have anything to do with the idle?...

Fotis

iTrader: (2)

when ur driving and ur coasting throw ur car in neutral and if the RPM dont go down then u got a leak in your intake somewhere after the throttle body...

THINGS TO CHECK:
#1 look at the back of your intake there is a sensor. see if the seal is good on it.

#2 see if you intake has a crack any where.

#3 on top of the intake u have the EGR hose since your is a 1998, see if that is leaking at all, if its been removed see if they capped it off well.

#4 last of all on the left of the throttle body there is a black hose with a rubber fitting on it it goes from the throttle body to the valve cover.. see if that is leaking at all

if none of that does anything take the intake off and change out the gaskets between it and the heads. u have 10 8mm bolts to take the intake off and of course 4 10mm bots holding ur fuel rail and injectors on...

if none of that fixes your issue PM me and ill give you my number to call me so i can help u better



bur TPS could be the problem but ive never seen those go bad.. try cleaning it with some non clorenated brake cleaner. see if that does anything

Transam9973

one thing you could try is spray Mass air flow cleaner in the MAF. I had trouble with my bolt ons 99 idle high intermently and that was what it ended causeing.

LS1WS6dreamer

iTrader: (1)

Idle issue could be Idle Air Control Valve. This idle problem crap seems to be sord of common because there is a lot of info going through google on it when I have searched in the past. Try the general maintenance and repair section on here. I had a 02 sensor that was acting up and it was causing a high idle going down the interstate, but not all the time just randomly.I replaced the 02 sensor. Started doing it again months or a year later and it ended up being the IACV. I replaced the IACV and it fixed it, but a year later its doing it again randomly. Whats weird is that when I come to a complete stop the idle goes back to normal. Good Luck

FASTFATBOY

iTrader: (23)

What is your TPS percent at idle?