Ok. I've been tracking down a high idle for a while now. EGR tube was broken, so I replaced it. Still high idle. Replaced big rubber hose under plenum. Still high. Could find no vacume leaks at all.
Today, I was looking at it, and discovered that the throttle cable is not letting the throttle close all the way. If I unhook the cable, it idles right down where it should be, just perfect. Hook it up, and it idles at about 2 grand.
So! What would make the throttle cable be too short? The bracket does not seem to be bent. I pulled the bolts out of the bracket, and if I move it towards the throttle body until the throttle is closed all the way, it is almost half a bolt hole off. I think if the cable would come out about another 1/8" it would be fine. The cable is very free in the housing. Also, just feeling up under the dash at the end of the gas pedal arm, there seems to be slack there when the throttle is closed, so what is stopping it from coming out the other end? Is there an adjustment at the front end of the cable?

the cable could be frayed somewhere in the cable guide?!?

just a thought.

does it seem to move easily, like with no friction on the gas pedal when you depress it??

good luck

mike

Yes, it does move very freely. No snags at all. This seems really strange to me. I am stumped as to how it got this way.

can you manually force the butterfly closed when the car is idleing to be sure it is snagged?
maybe someone messed With the set screw?

quote Originally posted by 85GTFiero: .... Also, just feeling up under the dash at the end of the gas pedal arm, there seems to be slack there when the throttle is closed, so what is stopping it from coming out the other end? ....

Look for the cable fray on the pedal end of the throttle cable. Fray here would keep the cable from going back into the sheath when you let off the gas, but not affect the slide of the cable when the pedal is depressed.

Pull the gas pedal out and bend the arm just a bit.

$Rich$ : Yes, when it is idleing, I can push on the linkage and make it close and it idles right down. With the cable hooked up it does not touch the stop screw. Unhooked, it shuts by itself.

RTNmsds: That was my idea also. I pulled out the big plastic piece that goes down the tunnel, and pulled the cable out. It looks fine. The last six or so inches of the cable has a sleeve crimped on it that slides into a larger sleeve of the sheath, and bottoms out. I trimmed about 3/16" off the sleeve that is crimped right onto the cable, and that gave it enough to close all the way. The cable moves very freely, with no hang up whatsoever. Only thing I can think of is over the years, dust and dirt got built up inside the outer sleeve, on the "bottom out" surface?

84Bill: I thought of this, but when I checked it, with the cable pulled tight, there was still about a half an inch of cable before it bottomed out on the pedal. It was bottoming on the sleeve.

I hated to trim the sleeve, as there has to be a reason it got like this, but I can not find anything, other than a possible build up in the outer sleeve. Thanks for all the ideas guys. Any more would be great. Even though I have it working fine now, I would still like to figure out how and why this happened!