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Variation on Idle Surge Issue

D

detroitiron2000

New CEG'er
Joined
Mar 31, 2008
Messages
25
Location
Bridgman, Michigan
Hi, searched but can't find the issue I'm having.

The car recently started having the idle surge issue but mine is mild, surges from 750 to 1000 rpm. But I also have a second surge and it occurs when cruising at a constant speed. Can this also be caused by the IAC valve? If so, why?

I'll be replacing the IAC this coming week but wanted to wait until maybe somone could shed some light on the "at-speed" surge.

Car is 2000 SVT, all stock.

Thanks, Don
 
The IAC would be a good possibility, even if the idle is just slightly surging. My IAC ended up being stuck open and just rolling down the road in 3rd would yield some slight bucking
 
Thanks for the ideas. I hadn't considered the PCV. I ordered the new IAC today...cripes they're expensive!! When I pulled the old one off it looked bad and failed the test for resistance given on teh Autozone site. When I replace it I'll check the wiring as well.

Again, thanks for the ideas!!!

Don
 
I have a similar problem but........

I have a similar problem but........

....I have already replaced the iac, pcv, maf, tps, egr, and anything else I missed, Also mine will rev to 3000rpm at times. It will continue with the clutch disengaged. Only when I come to a stop will the revving stop. Any ideas?
 
Sounds like you've got yourself a little throttle hang. There's a fix for it somewhere here (a moderator will probably post the link...) but really, all you're doing is installing a "restrictor plate" before the idle air control valve. If your wiring harnesses have gone bad, chances are your IAC wires are shorting somewhere in there.. One pin in the IAC plug is the "V-power." When you test that with a volt meter (positive to V-power, negative to ground) it should read close to 12 volts with the key on, engine off. Then the other terminal should be 0 volts and is the signal to the PCM. Mine read close to 12v on both pins because of a short in the harness so basically the PCM had no control over the IAC. So I found the signal wire at one of the main harness connectors next to the power steering hoses (V6, i didn't see if you have the zetec..), snipped it and spliced in a new wire which i ran directly to the IAC connector. Problem solved.
 
I do have the duratec engine. Could a moderator post that link, I have searched with no luck. Thanks for the info in the meantime.
 
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