fast idle

[DavidHenshaw]

1984 automatic 302 V8 carburated town car with 81,000 actual mlies.

The car developed a fast idle about four or five weeks ago. It's fine until its been driven for five minutes. After it warms up the idle begins to pick up. There's no tach but the car will maintain 45 to 50 mph on level highway without pressing on the accerelator.

I've replaced the PVC filter, air filter, and put a new idle arm control valve on. The white plastic diaphram part of the IACV was cracked so I thought that might be the problem. Got it on, took it for test drive and idle is still high.

Any ideas before I take it to a FORD dealer.


Dave

[Towncar]

Try here also.

[MagicRat]

Maybe the fast idle cam is stuck in the fast idle position. Sometimes a bit of carb cleaner or WD 40 can free up it's movement.