Hi. My 02 Monte SS 3.8 has a weird problem. On cold starts it idles at 1200 to 1300 rpm and as it warms up the idle increases to 2000 rpm. In drive it will gradually excellerate to 25mph without touching the peddle. Sometimes if I shut it down then restart it, it will idle properly. But as I drive it tries to get as high as 2300 rpm. The oddest thing about it is there are no codes in the computer. All my other gages read as expected. Has anyone had this with there Monte? I've never seen it on any other GM. Thanks for the help. P.S. The car has no modifications.

 

Hi MCF, I still need help with this problem.
02 SS HI Idle. I have replaced: MAS, MAP, IAC, FPR, Air Filter, Plugs, and a couple of vacuum line that were dry rooted.
Symtoms: Cold Start, engine starts at about 1500 rpm, as expected. But instead of decreasing the idle increases and will go to 3000rpm if I let it. So I shut the engine off and start it again. It goes to about 1300rpm and decreas to about 750rpm. Then when hot, the rpms want to stay at whateverevel I was cruising at. It drecreasesas I come to a stop to about 1200rpm but you can feel the engine trying to push the car. I put it in neutral and the idle jumps up to. 2000rpm the slowly decreases to about 1200rpm. It is also starting and stalling when the enjine is hot. I have to hold the gas at 1200 rpm for a minute to get it to stay on. Sometimes when at normal op temp I start it and it goes right to 3000rpm. Then I hav e to shut it off and start it again.
I would think its a vacuum leak except the symptoms are erratic as far as where it will idle. Sometimes I go over a bump and the symptoms change. When the idle is hi, you can hear Super sucking through the air filted. When I try to start it when warm, I get the catalytic smell. I have no check engine light and no loss of power that I can tell. All Iknow tells me itit's got to be the computer telling the engine its under a load. But even a code checker comes up empty. I'm seriously at a loss and need help bad. I'm only driving 10 miles a day, no highways and no weekend driving cause I'm afraid that would cause serious damage.
Anyone who may have seen this please help. I don't know were to turn next! :'(

 

Have you taken the throttle body complete off the engine and cleaned it?

The TB plate could be sticking from carbon buildup. Also, I don't see the TPS on your list of things you replaced. That could be going bad.

 

Thanks Chibi for your response! I knew I was forgettin something when I wrote this. The TPS and serpentine belt was also replaced. I have not taken the TB off yet but i have sprayed it with a TB cleaner. Usually by the time I get home its dark. And the misses always has the w/e planned. But that is one of my plans. Now that I got rid of those 22s I can feel whst the car is really doing.
Thanks again. If you think of anything else I should look at, I would be very grestful.
By the way, the car has 169000 miles. Thanks again! B-)

 

theres a vaccum leak check your brake booster line for leaks

 

Probably not if it's a steady idle at 2k, but possible.

 

hes checked everything else

 

he only sprayed the TB with cleaner

 

It's a vacuum leak, same thing that happened to mine. Spray some starter fluid on all of the areas where the gaskets meet up at.

 

Wow! I didn't mean to cause a debate. Thanks to all of you. I have changed some of the vacuum lines but not all. But the condition of those I have changed suggests that I should change them all.
The idle speed has not been steady.
1st clod start: 1500 rpm. Then something comes on in the engine compartment and within a minute it works it's way up to 3000. Restarts: 1500 then downloads to 750 as the motor warms. After about 5 minutes of driving the engjne surges. Then when I stop and put it in neutral it surges up to 2000 then come down to 1500. As I am driving, I step on the brake it serges aboht 300 rpm then comes back down 300. Then as I slow down it will idle down to btwn 1200 and 1500.
I will take a look at all my vacuum lines today. The TB will come off tomorrow morning. I'll pick up a TB gasket and a Brake booster hose tonight. My deepest appreciation for all the help! B-)