BADSS

iTrader: (7)

I THINK I have a vacuum leak- haven't located it yet. I have two potential sources of a vacuum leak- the EGR o-ring (where it attaches to the intake) was cracked, and the coolant lines under the manifold were not plugged and re-routed. The installer just crammed the intake down on top of them. Onfire and I are taking the intake off and reinstalling it properly next week. My car will idle between 1200-1500 RPMs, then slowly idle down to 900. Used to idle at a rock-solid 750 RPMs. When I shift gears, the RPM's only drop to about 2000 RPMs. I'm not sure if this is exactly what you are experiencing, but it sounds similar.
I also get occasional surging at idle- it is not a steady idle. When I turn the A/C off, the idle goes up, and then comes back down.

LightweightZ28

iTrader: (2)

My car does this as well and always has. I was also told by the dealer that it was normal. I also drove another 2001 Z28 that did as well. Doesn't seem to be hurting anything so I haven't worried about it.

Red02LS1

this topic is going on at the SLP forum here
http://www.hoodscoop.com/cgi-bin/ult...c&f=2&t=002802

10thHawkRagtop

I dont like the slow decell that my 2001 Firehawk has and believe there is something wrong,My 2000 firehawk downshift or run it up to 5000 rpm and let off ...count to 3 and it decells.I also have noticed in cooler weather it doesnt do it (hang)...i just cant deal with this crap of downshifting when comeing to a light in traffic and it just wants to keep going...push in the clutch and the engine runs up to 2000 to the extream case of 5500rpm...that just isnt right and is unsafe.....I just want my 10th rag fixed and dont care how long it takes.

Sapient

Yeah, that sounds more like a possible vacuum leak. I think he definitely has something else going on with his car though. I checked out that link to the SLP board, one guy there has been dicking around with GM since August, with his car. Still no answer on the problem, hard as that is to believe... <img src="images/icons/rolleyes.gif" border="0">

Red02LS1

I'd like to note that the car is only slow to return to idle when moving, or shortly after comming to a quick stop. If I rev up the engine when still, it returns to idle quickly. If I'm driving and put in the clutch, the RPMs go down super slow, but once they return to idle and I rev up, its normal again. Its pretty frustrating. There doesnt seem to be a vacume leak, as there is NO surging at idle, and the idle is smooth. It seems to me as if the IAC is staying open when the RPMs just float around.

Red02LS1

ttt

Colonel

I've had this problem before but there are a few things that can cause it.

Check your TPS at idle. It should be .4v or less. It sounds like your TB might not quite be closing completely. And no, you can't tell that small of an amount by simply looking at it. This is what my problem was once.

And yes, a vacuum leak could also cause this. This would be indicated by a very low IAC Motor Pintel Position at idle. What does yours say?

If both of these things check out then you should try pushing in the IAC pintel (take it off and push the plunger all the way in) and then performing the idle relearn procedure. I can give you that if you don't already have it.

Red02LS1

wow, I thought this post was hopeless, thanks Colonel. What should the IAC count be at at idle? cruising? what about the TPS? also, what could I look for on Auto tap? I have the car in the garage for the winter, and only 1 person I know has autotap, so I will try to get the car a-tapped in the spring. What is the idle relearn procedure? What is really weird is if I go up to 5,000 in 2nd or what ever gear, let off, it will just stay there for a while at the same speed with no deccel, then mabye 10 seconds later, the decellaration will kick in, and you can tell by a change of exhaust tone as well.

WeatherGuy

FWIW, I once had symptoms like this, but it was after I installed a FTRA on my car. At highway speed, the engine would not slow down, and if I pushed in the clutch it went UP to over 2000 RPM if the engine had been below that and stayed there.

My suspicion was that the air induction was so good that it was messing with the TB blade closing, but I was never able to confirm that. What happened to me is obviously different from this case, but I wonder if it points in the right direction.

WeatherGuy

[quote]Originally posted by Red02LS1:
<strong>I already tried switching back to the stock lid and blocking the FRA. It did not help.</strong><hr></blockquote>

Did it get worse when you did the FRA and lid and then not get better, or did those never have an effect? I don't want to lead you down the wrong path, but I am also trying to figure out why I used to have that problem.

02SSPL

I have a very similar problem on my 2002 SS. On the SLP site thread someone mentioned it was much worse with the A/C on. Mine is exactly like that. The idle goes up with the A/C on, but as soon as you turn it off, the idle returns to normal. I took it to the dealer, and they also said they couldn't find anything wrong. It hasn't bothered me much this winter because I haven't been running the air. It is getting warmer now, so I will soon see if it is still doing it. PL

BLOWNMERO

Maybe you left your cruis control on... hahaha

zombiedude

iTrader: (1)

I worked at a Chevy dealership untill 2 months ago. I've since opened my own 1 horse shop.A few Camaro's and a lot of vette's came in doing all kinda weird stuff. This was mostly because of Bad Grounds! Block, Body, and Computer Grounds. They tried PCM's, BCM's and the like. Cleaned the grounds Everything came back to normal. They will "look good" but take it off and you'll see corrossion. Hope this helps <img src="gr_images/icons/wink.gif" border="0"> Also do you have ASR ?

[ February 14, 2002: Message edited by: zombiedude ]</p>

Red02LS1

I already tried switching back to the stock lid and blocking the FRA. It did not help.

Red02LS1

Its exactly the same with the A/C on. No I don't have ASR. Its not really an idle problem as much as a lack of decellaration, or rpms not dropping much between shifts. I'm still looking for what IAC counts should be over the rpm range, or what to look for on A-tap.