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.
Check the throttle cable and spring to be sure it operates freely. Maybe wd 40 may correct.
August, 16, 2011 AT 10:18 PM
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.
August, 16, 2011 AT 11:28 PM
I meant PCV, not PVC. Obvious, but had to correct myself.
October, 29, 2011 AT 8:25 PM
Did you guys resolve it? What was it?
October, 31, 2011 AT 12:06 AM
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.