1989 Ford F-250 rough idle, hesitation

Tiny
344
  • MEMBER
  • 1989 FORD F-250
  • V8
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
My truck will idle rough after it warms up. Also when driving it hesitates as if it was missing, especially at low speeds. Will idle rough when stopped in gear. I've had it tuned up ( plugs, wires, etc.) Will run fine for a while when cold. No problem starting. No problem at highway speeds. Was wondering about idle control valve?
Thanks.
Sunday, July 27th, 2008 AT 11:10 AM

3 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
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Sunday, July 27th, 2008 AT 11:13 AM
Tiny
344
  • MEMBER
  • 2 POSTS
Thanks for the suggestion! I'll give it a try. Thanks again, 344.
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Sunday, July 27th, 2008 AT 6:26 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Let me know.
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Monday, July 28th, 2008 AT 1:08 PM

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