1800-2000rpm constant idle

[Naaman]

Just curious, what is the weather like in KY right now? Here in AZ, it's fairly cold in the mornings (mid 30s) and when I start it up, the idle goes straight to about 1400 and settles into 1000 over the course of a few minutes (as indicated by the tach... the CKP reports 200 rpm fewer than what the tach shows).

If you are able to isolate the problem and it turns out to be the throttle body, let me know. I have a completely stock one that I'm not using.

[theorangeguy]

this really sounds like a vacuum leak so your tune shouldn't matter because it wont help with this situation...do you hear any whistling noises when you are under throttle or any sucking sounds that are out of the norm? These motors have a hand full of spots that are notorious for having vacuum leaks.

My last vacuum leak was right here...New gasket solved the problem. Cost like $2 and fixed my idle issue...all I had to do was press down on it and wiggle it a little and the idle would start changing. It would be worth unbolting this inlet and reseating the gasket to eliminate this from the equation...takes like 2 minutes.



Im also sure this was already asked "I didnt read every post" but have you cleaned the MAF...? I saw somewhere that it was descreened...

[cammedta]

For some reason when my 98 worked the idle was around 900-1000 rpms even with a Frost tune. I have a LS6 intake and P&P S2 Throttle body.

1500 I agree is too high. On the throttle body how high is the screw?


Have you tried using some carb cleaner to check for vacuum leaks?

Have you tried the disconnecting the MAF yet?

Yeah the idle screw is backed all the way out. I've sprayed carb cleaner everywhere and no sign of vacuum leaks. Unhook the maf and it idled around 1400 lol

[cammedta]

Just curious, what is the weather like in KY right now? Here in AZ, it's fairly cold in the mornings (mid 30s) and when I start it up, the idle goes straight to about 1400 and settles into 1000 over the course of a few minutes (as indicated by the tach... the CKP reports 200 rpm fewer than what the tach shows).

If you are able to isolate the problem and it turns out to be the throttle body, let me know. I have a completely stock one that I'm not using.

It's in the 30's, has been for about a week. It doesn't matter how long I drive it the idle never comes down until it starts loading up where it's so rich and it's killing the plugs then it will try to die. Hey man I really appreciate that if that turns out to be the problem I will let you know. Thanks a lot.

[cammedta]

this really sounds like a vacuum leak so your tune shouldn't matter because it wont help with this situation...do you hear any whistling noises when you are under throttle or any sucking sounds that are out of the norm? These motors have a hand full of spots that are notorious for having vacuum leaks.

My last vacuum leak was right here...New gasket solved the problem. Cost like $2 and fixed my idle issue...all I had to do was press down on it and wiggle it a little and the idle would start changing. It would be worth unbolting this inlet and reseating the gasket to eliminate this from the equation...takes like 2 minutes.



Im also sure this was already asked "I didnt read every post" but have you cleaned the MAF...? I saw somewhere that it was descreened...

That's for the egr isn't it? I have an ls6 intake it doesn't have that. Yep I cleaned the maf and no change either. Driving me nuts. I'm seriously about to order the 6ls box and victor jr intake and put a carb on it.

[Firebirdjones]

Sounds like you really need access to HPtuners, drive and log that thing and see what's really going on. I question the tune itself as well because you are getting all those transmission codes. If it were tuned at all, those trans codes should have been taken care of the first time around with a manual trans base file to start with.

[pajeff02]

No way I would swap our car over to a carb setup -- the cost of the parts, mods to the fuel system, and the question of hood clearance all negate that. That's a whole lot of money and work to fix an idle issue. Too bad you didn't live closer to PA -- we'd have that thing figured out in a hurry. For around $550 or so, you can pick up HP Tuners Pro. If you are a GM fanatic like most of us, it is a great tool to have.

[Firebirdjones]

I was going to say the same thing. Switching over to a carb would cost you much more than a good dyno tune would so it's really not a cost effective option.

By the time you buy the intake, the MSD controller, and a good HP carb you'll be in it for $1500. Then all the little stuff like the fuel system and hood clearance that Jeff mentioned (people seem to forget to take that into consideration) You'll need to run fuel lines, a good regulator, etc...and these 4th gens suck for hood clearance not to mention half the engine sits under the cowl.

I'm all for a carb swap in a retro application, but on a car like this that was designed and born with this setup, I'd stick it out, find and fix the problem, and enjoy it.

[SMWS6TA]

I'd do like Jeff suggest, borrow a TB from someone to rule it out. Otherwise it's time to check the tuning. It might be worth it just to talk with Frost and see what he thinks. He has one of the best mail order tunes out there. (cost $150) You fill out a worksheet, mail the ECM and he can tune it based on what you tell him. Get it back in less then a week in 95% of the time.

[jb3golf]

That's for the egr isn't it? I have an ls6 intake it doesn't have that. Yep I cleaned the maf and no change either. Driving me nuts. I'm seriously about to order the 6ls box and victor jr intake and put a carb on it.

Let us know when you are able to ascertain a throttle body to confirm if thats the problem....I would also re-check all the pins in your pcm that are related to your dtc's...I had a nightmare gremlin on my 98 recently and it ended up being a semi loose pin in my pcm.....keep us posted...