My car just recently started to idle extreamly high around 1800-2000 rpm. I adjusted the TPS and nothing and cleaned the IAC. What could be the cause of this? I may be selling the car and can't have that. I don't want to sell it but the car needs so much work i might be better off getting a v-8 Any advice would be great

 

Maybe a Vacuume leak?

 

i had two big vacuum leaks (a couple hoses actually undone) and the highest it ever idled was 1000, so i doubt that's it...

it could be a number of things... i would check the cap and rotor first. i had a really corroded cap when I got the car and it idled up to almost 2 grand a couple times, then after a couple days the tach started getting really erratic and the car would surge and slow down and sometimes wanna die

check your timing with the EST hooked up, and give it gas, see if it still advances while you give it gas, maybe an ECM problem

or, maybe ya CTS is busted, and the ECM always reads cold (the guage and the ECM reading are two different sensors on most of these cars) so it keeps dumping extra fuel trying to warm it up

 

I'd just keep looking at any vacuum leakage possible.
Thats your car in the pic?
Very nice.
I'm into repainting my Firebird to look like that.

 

I'll work on her today. I think I will be selling her because I lost one of my jobs and now I only work Assistant manager at Stop N Shop in Mass. Can't afford to keep it and meet the bills Thanks for the compliment. I love the way it looks with the Formula rims on it

 

Try adjusting the idle speed screw with the engine running. Right now, my engine idles at 1300 no load and ~900 in gear, and with the engine running I can crank it down to the factory recommended 700 RPM when warm. However, at this setting, when I try to start it cold it will stall, so I'm leaving it the way it is for now until I find the correct PROM...

 

Maverick, you idle at 1100? I'm getting a code 34 and was wondering if I should increase my idle up a notch from the 600-700 it's normally at higher. Maybe more airflow no code is my logic. My car is a shift so I don't really need it up that high for anything else, however, it does tend to stall when it's cold.

CamaroGuy I hear your pain about selling your car despite the problems you've had with it. I've read many of your posts. It looks cherry.

Does it still look like the pic?

Chevman.

 

Well, lemme see. Now that the engine FINALLY runs right, I idle at around 900-1000 no load and about 700 or so in gear.

Chevman, if I were you, I'd go ahead and replace the MAF relay (located right next to the MAF on a bird, on the passenger's side of the radiator, bolted in the corner between the headlight support and the part that becomes the radiator support, right above the electrical junction block) before I went ahead and bought a new MAF, which happens to be over $200. You can also test the MAF by unplugging it, or by tapping on it with the engine running. Also, check to see if the terminals inside the MAF connector are tight on the ones inside the MAF...

 

Hey Mav,

So what was your solution to remedy the high idle? Mine's doing the same thing. I've replaced nearly every sensor, vacuum hose, plug wires etc, etc.
New PROM for the ECM then?

Thanks

 

Have you tried cleaning out your throtle body? maybe there is carbon build up along the edges causing the throtle body to be stuck slightly open makeing it suck more air in?

 

I've cleaned the TB, cleaned and lubed linkages and cables. When I disconnect the ECM (cold engine) I can get it to at 1000 using the adjustment screw, any lower she dies quick. When I get 1000 and re-connect the ECM it idles at 1200.

When she's warmed up I can get it down to 900 but on the next day's cold start she refuses to idle unless I adjust the idle screw up to 1000 again.

If I keep my foot on the gas until it warms up, like five minutes, sometimes more, she'll eventually idle at 1200 again.

 

maybe you have a bad intake gasket. Spray some TB cleaner around the intake and see if it stumbles.

 

coz, you having any other problems, such as a stumble on acceleration or a misfire at idle?

I had the same problem. It could either be spark or fuel related. In my case, I still need to replace my factory HNR code PROM with an 89 HNL PROM to get my cold fuel mixture correct. I have gone through the entire ignition system from the pickup coil to the spark plugs (the pickup is the ONLY part that is not new), and replaced four out of six fuel injectors (hoping to pick up a couple more sometime soon) and I have the problem knocked down to an ECM calibration error (not enough fuel, CSS doesn't work properly and provides too much fuel), and I hope the newer chip will help.

Mine doesn't need gas for quite THAT long though. It did during the winter (I know ), but that was before I started putting good parts in. Now, I only need to hold the gas maybe 45 seconds or so.

Also, check for fouled plugs, overly advanced timing (mine is set at around 20* base and I'm going to reset it tomorrow), and a clogged fuel filter. Check you vacuum reading, if you can. Intake vacuum should be near about 14" Hg or better. It almost sounds to me like you have a misfire due to lack of fuel on cold starts. What year is your car?

 

Mav, I have a '92
I just came in from the garage and have discovered a couple of new things. With the base timing at 8* and ECM connected the timing light on it I noticed it'd occasionally miss a flash so I'm thinking "bad wire/plug" (just put new wires, plugs, coil on.) So I moved the light to a different cylinder and it still dropped occasional flashes. Disconnected the ECM connection drops no more strokes. Reconnect ECM, drops. So with the ECM disconnected and ensuring the timing is still 8* and I can get her idled down to 700 and it runs fine, even down the road.

So I'm definitely leaning to an ECM/PROM issue. So I'm going to debating whether to start with just a new PROM or shoot the moon and replace the entire module.

 

Umm, 8* BTDC is a little too far retarded. Stock is 10*, and I am currently at about 18* BTDC. I have the same miss type scenario you do, but I am not sure whether it is normal or not. Both of my ECM's do it, regardless of whether I have the new ICM or the old one in. I know my plugs and wires are good, unless one suddenly decided to die on me, and I know the coil is good. Hmmm... Have to wait until I get my '89 ECM in the mail to find out what is up with that...