1997 Ford Expedition Fast Idle

1997 FORD EXPEDITION
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XPODIOUS1
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  • 1 POST
I have a 1997 Expedition with 219,000 miles on it. I am currently having a fast idle problem that I can not resolve. The vehicle idles at about 800k on cold start but if you touch the pedal even slightly it will idle up and fluctuate between 1300 and 1500 and idles at about 1100 while in gear. If you hit the gas and release it the idle only returns to about 1600 and will gradually climb to about 1900 over the next minute. Idle is always high on warm starts and after driving. No problems with stalls or cutouts. I originally had a code of P0320 which led to testing and changed the original IAC valve as it was showing low resistance readings (approximately 4k ohms). The problem still persists. I performed voltage readings of the IAC’s connector with the ignition switch in the “ON” position as well as resistance of the new IAC which all checked good. The MIL light is not on and there are not codes in memory. What would be my next logical step in rectifying this problem?

I thank you in advance for you time and consideration.
Feb 14, 2006 at 6:21 AM
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LOVESCARS
  • ✓Experienced Mechanic
  • 359 POSTS
check the throttle cable and spring to be sure it operates freely. maybe wd 40 may correct.
Feb 14, 2006 at 10:11 AM
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PROBLEMSASWELL
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I've got a 1997 Expedition with exact same issues. I've replaced PVC valve and IAC unit. Problem still there. Next will be the "heated PVC valve hose" behind the throttle body. Proper name may be called the PVC Valve Assembly. I think I've got a vacuum leak, as the hose is dried out and in bad shape. I'll let you know how it goes. If you find the problem and are able to fix, let me know what it was. Glad I'm not the only one with this problem.
Aug 16, 2011 at 3:18 PM
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PROBLEMSASWELL
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I meant PCV, not PVC. Obvious, but had to correct myself.
Aug 16, 2011 at 4:28 PM
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FIXITMR
  • ✓Experienced Mechanic
  • 9,989 POSTS
did you guys resolve it? what was it?
Oct 29, 2011 at 1:25 PM
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PROBLEMSASWELL
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I replaced the PCV vacuum hose running from the PCV valve to the back of the throttle body. Old hose was a bit soft at the bend, somewhat broken down. Not as bad as I thought it would be though. It's been a month and a half without a high idle problem. I think that did it. So simple. Nice surprise for once. Hope this helps someone out there.
Oct 30, 2011 at 5:06 PM

Suggested Repair

Check that the throttle cable and return spring move freely. Also inspect and replace the PCV vacuum hose from the PCV valve to the back of the throttle body if it is soft, cracked, or deteriorated; replacing that hose resolved the same high-idle condition.

Conversation Summary

A 1997 Ford Expedition 5.4L idled near normal on a cold start, then rose and fluctuated after slight throttle input, stayed high in gear, and climbed further after a throttle blip. Warm restarts and driving also produced a high idle, with no stalls and no codes after the IAC valve was replaced. An expert advised checking that the throttle cable and spring operate freely. Another owner with the same symptoms replaced a deteriorated PCV vacuum hose between the PCV valve and the back of the throttle body and reported the high idle stayed gone for a month and a half.

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