High idle

[Jorge1958]

Ok folks. Got a question. My 86 SS runs really well but i have a concern. When i fire her up cold the choke comes on as it should. After a couple minutes of running it comes down depending on outside temp. Yesterday i took her for a spin. At first it would idle at 700 or so rpm. But after a half hour or so of driving i noticed at idle it was around 1100. And it wouldnt come off that. It ran great. Just a high idle. Why would it be fine for the 1st say 1/2 hour of driving and then all of a sudden jump up to 1100? I have changed all the vac hoses and the AC was not on.

 

[Xcellr8r442]

Ok folks. Got a question. My 86 SS runs really well but i have a concern. When i fire her up cold the choke comes on as it should. After a couple minutes of running it comes down depending on outside temp. Yesterday i took her for a spin. At first it would idle at 700 or so rpm. But after a half hour or so of driving i noticed at idle it was around 1100. And it wouldnt come off that. It ran great. Just a high idle. Why would it be fine for the 1st say 1/2 hour of driving and then all of a sudden jump up to 1100? I have changed all the vac hoses and the AC was not on.

Could be bushings worn in primary shaft....if a quadrajet....make sure throttle is returning to idle position....stronger return spring will help temporarily...

 

[Clone TIE Pilot]

Could be a vacuum leak somewhere, such as carb mounting gasket, carb gaskets, intake manifold gaskets, worn throttle shaft, leaky brake booster, stuck PCV valve, leaky PCV gromet, leaky EGR valve, etc. Hoses are just the tip of the vacuum leak iceberg. You can make your own Teflon bushings to fix worn Qjet throttle shaft bores if they aren't worn too badly.

 

[Jorge1958]

I have previously done the vacumn lines. I will chk the throttle shaft bushings.

 

[airboatgreg]

Choke may not be coming off of fast idle cam. Secondary throttle plate open.

 

[airboatgreg]

Could be a vacuum leak somewhere, such as carb mounting gasket, carb gaskets, intake manifold gaskets, worn throttle shaft, leaky brake booster, stuck PCV valve, leaky PCV gromet, leaky EGR valve, etc. Hoses are just the tip of the vacuum leak iceberg. You can make your own Teflon bushings to fix worn Qjet throttle shaft bores if they aren't worn too badly.

When i had my shop i used Briggs and Stratton valve guides. Can get you number if you want

 

[Jorge1958]

So i chkd the throttle shafts for play and there seems to be some play on both of them. Especially the primary throttle shaft. I guess im gonna have new bushings put in it. Anybody know of a reputable place out there that can do this? Hard to believe they have play in them when the car only has 22 thousand miles on it. Oh well. I hope that cures the issue. Everything else looks great.

 

[pontiacgp]

So i chkd the throttle shafts for play and there seems to be some play on both of them. Especially the primary throttle shaft. I guess im gonna have new bushings put in it. Anybody know of a reputable place out there that can do this? Hard to believe they have play in them when the car only has 22 thousand miles on it. Oh well. I hope that cures the issue. Everything else looks great.

did you check this?.....

Choke may not be coming off of fast idle cam. Secondary throttle plate open.

 

[Jorge1958]

No i havent yet. I will check that next weekend. But it seems if the choke was not coming completely off i would think it would run like crap. Runs fine. Just a high idle.

 

[pontiacgp]

No i havent yet. I will check that next weekend. But it seems if the choke was not coming completely off i would think it would run like crap. Runs fine. Just a high idle.

he didn't say the choke wasn't coming off, he said the choke fast idle cam is sticking which is not unusual with a car that has been sitting for a while and a couple of shots of carb cleaner/lubricant can cure that.