Why Random Fast Idle?

bretamo

Member
May 13, 2005
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Stock 92GT with performance chip experiencing a random fast idle, which just emerged over the over the past month.

Here's the deal, the car will idle around 900rpm at start and throughout most driving conditions, but at some stops the idle will rise to 1200rpm and just stay there. When this happens, I'll put the car in gear to put load on the motor to bring the rpms down, but it will immediately rise back to 1200rpm when I engage the clutch. The problem will go away if turn off the ignition and restart after about 20 seconds.

Last night the car developed an exhaust leak after the Oxy sensors but before the mufflers. This just happened last night and I initially thought the problems were unrelated.... but I can't help but wonder if they really are related.

Stangnet gurus, what is your diagnosis?
 
I doubt they are related, but who knows? :shrug:

Check out the surging idle checklist that jrichker wrote at the top of the 5.0 tech forum.

That sticky is pretty complete, and should solve your problem.

jason