F-150 Rough idle

Discussion in 'Mechanic and Repair' started by seasonal services, Nov 22, 2004.

  1. seasonal services

    seasonal services LawnSite Member
    from ohio
    Posts: 32

    I have a 93 f-150 auto with 136,000 miles, it has always run good til about 2 weeks ago, it started idleing a little rough. Then about the last three days it is really bad. sometimes when i start it up in the morning it will rev up to about 2000 rpms then stall, it will do this like 3 times then it will stay running but still idles rough. It also like boggs down or stutters when i take off but once i get going it runs fine. Any help is appreciated thanks.
     
  2. CCWKen

    CCWKen LawnSite Member
    Posts: 113

    Does the check engine light come on?

    Sounds like ignition, if you don't get a light. When was the last time plugs and wires were installed?

    Forgot to mention:
    May also be Idle Air Control Valve.
     
  3. seasonal services

    seasonal services LawnSite Member
    from ohio
    Posts: 32

    Check engine light does not come on, I took it to auto zone and had them plug it in to tester and it didnt find anything. i bought the truck abought 9 months ago and have put about 12,000 miles on it. i have never changed plugs and wires but i took a plug out and it appears fine, gapped good.
     
  4. PLM-1

    PLM-1 LawnSite Bronze Member
    Posts: 1,640

    Could also be an oxygen sensor. If that is the case and you don't want to replace them right now you can clean them with brake cleaner and that will get you by for a while. You may even just try it now so you can check that off the list of possibilities.
     
  5. CCWKen

    CCWKen LawnSite Member
    Posts: 113

    Output from the O2 sensor(s) don't get processed until the engine warms up. If the engine races on start up, it's more than likely the IACV.

    ken
     
  6. PLM-1

    PLM-1 LawnSite Bronze Member
    Posts: 1,640

    Now that i get to thinking about it you are right! Good job catching me! :dizzy:
     
  7. seasonal services

    seasonal services LawnSite Member
    from ohio
    Posts: 32

    i was told by the guy at auto zone it could be the idle air control valve. H told me to take it off and clean it, so i did i sprayed brake parts degreaser in there and slid the rod back and forth. It seems to have smoothed out the rough idle a little bit, but it still revs up real high when i start up. Tomorrow i will probaly just replace it and see what happens.
     
  8. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Posts: 2,697

    Throttle Positioning Sensor. Fords are notorious for those going out.
     
  9. jaybird

    jaybird LawnSite Senior Member
    Posts: 272

    our 97 150 acted something like that turned out to be intake gasket.
     
  10. steinerguy

    steinerguy LawnSite Member
    Posts: 63

    Which engine/transmission is in this truck? Hard to be good at diagnostic if we don't know which one. I had an 88 with the 5l and the crossover tube on the back of the engine corroded off and I would have never found it without help..... but that doesn't exist on all.......

    Thanks,
    Joel
     

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