1989 Ford F250 rough idle , hesitation

1989 FORD F-250

85,000 MILES • V8 • 2WD • AUTOMATIC

344

MEMBER
2 POSTS

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........

Jul 27, 2008 at 4:10 AM

MERLIN2021

✓Experienced 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

Jul 27, 2008 at 4:13 AM