I have a '94 FD with 27K miles on it. Periodically, at cold starts, the engine will race at idle to about 3K RPM before finally droping down to a normal speed after about 20 seconds or so. This probably happens about once a week, and only first thing in the morning after the car has been sitting all night. Any ideas? I imagine that there is some kind of valve that adjusts throttle position at idle based on temperature. Could this valve be sticking?

 

That's normal. You might want to blip to throttle to warm it up before you drive.

 

Only once in a while???
The idle should always start at 3K for 5-15 sec when the engine is completely cold. The manual calls it "accelerated warm up". Many people do not believe this is good for the engine or the turbo.
If u tap on the gas, it will drop out of the accelerated warmup mode. Or if u start the car in gear, it won't even go into the mode. (That may be why u said once in a while, because u start the car in gear sometimes?)
It's up to u, but there is nothing wrong with the 3k idle on a cold start.

 

The 3k is normal. If you think it is killing your car you can always start the car while it is in 1st gear. That way it will only rev up to like 1.5k or so. If you forget then just put the clutch in and hold the car in first gear after starting it, as long as you hold it there for like 10 seconds then the revs should die back down to 1.5k

 

Thanks for the input. My car hasn't been starting in this "accelerated warmup phase" until the last few weeks or so. Probably because I live in Houston and we are justed starting to get some cold weather. I think I will start the car in gear from now on. It doesn't seem like it is too safe to rev that high right away.

 

Most of us long time FD owners, have removed the hose and metal pipe from the AWS solenoid and have installed a blocking plate. It helps to clean up the area around the throttle body.

 

thats just something you have to live with when u get a fd.

 

unless you have a Power FC