Bizarre high idle problem
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Joined: Jul 2002
Posts: 87
Likes: 0
From: Vancouver BC
Bizarre high idle problem
Hello,
I've been having some trouble with my idle lately. When I start the car, regardless of temperature, it idles normally. But as soon as I start driving a bit, once I put the clutch in the idle only drops to about 1500rpm! So at a stop light it'll sit there and idle at 1500rpm the whole time.
If I shut the car off and start it again, it will idle normally until the driving begins.
What in the hell could be wrong?
P.S. Turning the idle screw out has no effect -- it's already not even touching the throttle!
I've been having some trouble with my idle lately. When I start the car, regardless of temperature, it idles normally. But as soon as I start driving a bit, once I put the clutch in the idle only drops to about 1500rpm! So at a stop light it'll sit there and idle at 1500rpm the whole time.
If I shut the car off and start it again, it will idle normally until the driving begins.
What in the hell could be wrong?
P.S. Turning the idle screw out has no effect -- it's already not even touching the throttle!
Instructor
Joined: Mar 2003
Posts: 217
Likes: 1
From: Buffalo MO
Re: Bizarre high idle problem (VetticusSupersonicus)
if your idle adj screw is not touching, then it is in the high idle mode. there is a weight on the side of the carb that falls once the car warms up. this allows the carb to reduce idle. once the weight falls, it should allow the idle set screw to touch the boss on the carb. by the way, most cars with a standard trans usually has a high idle of about 1300 rpms and a low idle of about 800 rpms. also, if it has a idle solenoid for A/C that can effect it. good luck :flag
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Re: Bizarre high idle problem (VetticusSupersonicus)
Hello,
I've been having some trouble with my idle lately. When I start the car, regardless of temperature, it idles normally. But as soon as I start driving a bit, once I put the clutch in the idle only drops to about 1500rpm! So at a stop light it'll sit there and idle at 1500rpm the whole time.
If I shut the car off and start it again, it will idle normally until the driving begins.
What in the hell could be wrong?
P.S. Turning the idle screw out has no effect -- it's already not even touching the throttle!
I've been having some trouble with my idle lately. When I start the car, regardless of temperature, it idles normally. But as soon as I start driving a bit, once I put the clutch in the idle only drops to about 1500rpm! So at a stop light it'll sit there and idle at 1500rpm the whole time.
If I shut the car off and start it again, it will idle normally until the driving begins.
What in the hell could be wrong?
P.S. Turning the idle screw out has no effect -- it's already not even touching the throttle!
Start by inspecting the throttle cable. Does it move freely? Does it snap shut consistently? Is the cable housing clamp secure? Then disconnect the throttle cable and just observe the movement of the shaft and linkage. Make sure the lever hits the stop screw before the primaries bind in their bores and make sure the choke and other linkage move freely and is repeatable. Do this when the engine off and warm so the choke lockout is not a factor. The return spring should snap it shut every time, regardless if the cable is attached or not. The only time the lever will not fully return to the screw is when the choke is either fully or partially engaged. If this is the case, you can manually verify by releasing the fast idle cam and the primaries should close.
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Re: Bizarre high idle problem (VetticusSupersonicus)
I had a high idle problem similar to yours. It was a carb problem. Turns out that the holes in my throttle plate that the primary shaft runs through are a bit worn. This resulted in my primaries not closing all the way, but only when the throttle return springs are attached to the carb. I disconnected the springs and the primaries closed easily but as soon as the springs were re-attached they would somehow pull the primaries just enough in like a sideways direction that the primaries would bind before closing all the way. While driving I could tap the gas really fast and the primaries would close all the way. To fix this I connected the springs to a different location on the intake manifold. Otherwise I would have to get the primary throttle plate drilled out and rebushed, would cost approx $100 (CDN).
One other thing to check is to make sure your mechanical advance weights return freely to thier home position, make sure they aren't getting stuck out. Good luck!
One other thing to check is to make sure your mechanical advance weights return freely to thier home position, make sure they aren't getting stuck out. Good luck!
