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02 f-150 4.6 shake

Discussion in 'Ford Trucks' started by rancherman84, Dec 5, 2009.

  1. rancherman84

    rancherman84 Senior Member
    Messages: 196

    ok,new to me truck,bought with 34,000 on it,now has 42,000 on it.truck has a small shake at idle,above idle down the road all seem normal.to back to ford dealer,they said it needed an injector fluch/cleaing and spark plugs,well i told them to do injector flush only,as i can change plugs(besides they wanted a truck payment to change plugs).so i changed plugs,gapped them to spec on emmisions sticker(old plugs were fine,nice and brown/tan)no change in shake at idle.
    so took back to ford dealer again,said it had bad no.5 coilpack,garanted it would fix it,and they would pay parts because the plugs didnt fix it.so i said go ahead with repair,they did,truck was better for a day or so,now its back to shake at idle.
    you guys have any thoughts,no fault codes or engine lights at all,i am a fairly good wrench on diesels(imho) and can fix about anything,but this dam 4.6 has me pulling my hair out.
  2. .5racer

    .5racer Senior Member
    Messages: 132

    Its another coil pack , most recomend to change them all at the same time ....PRICEY
  3. purplehavoc

    purplehavoc Member
    Messages: 97

    If it is another coil pack you should be setting a miss fire code.
    Those motors seem to be finiky with the type of plugs they have in them as well.
  4. .5racer

    .5racer Senior Member
    Messages: 132

    I've replaced three now with no code. Mines a 2001 model
  5. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    You did use lots of dielectric grease in the plug boots? Do the coil pack ends too.
    Anti-seize on the plug threads?
    Try having it run in the dark and moving the plug wires around. Look for little blue sparks or changes in the idle. Could be a vacuum leak too. Check all the hoses and connections.
    Some stuff will never throw a code unless it's a big problem. Make sure all your wiring plugs are fully seated. Check the coil pack for cracks and carbon tracking. And all else fails the offending part or sensor will finally die and you can find it.
  6. grec-o-face

    grec-o-face Senior Member
    Messages: 485

    These motors are NOTORIOUS for spitting coils. You can get 'em cheap enough at your local parts store and they're easy to do.
    You won't always get a MIL light from a bad coil either. My supercharged mustang used to go throw coils without triggering a light all the time. The best one's I've found are "STANDARD" brand. I've even gone the aftermarket route like ACCELL and MSD... both are junk. It's also very common to find a bad coil - fix it, then have another one go within days.
    I've done TONS of them.
    Oh, and like MickRig said; DIELECTRIC is your friend.
  7. rancherman84

    rancherman84 Senior Member
    Messages: 196

    thanks guys,yes i used never sieze on plug threads,used platnum a/c plugs from carquest.this 4.6 has the coil over plug deal so no wires.and good way to check them with a DVOM or something?
  8. deckboys

    deckboys Senior Member
    Messages: 198

    i know it sounds like a waste of money but i would put the ford oem plugs in.... i have a 98 4.6 and i tried bosch, champion, and none of them compared to the oem ones
    get a can of throttle body cleaner and clean the idle air control.. as well as the throttle body..
    i've changed my coil packs and wires and have good vacum and fuel pressure...

    every now and then i get a rough kind of lump from the motor at idle but anything higher it goes away.
  9. rancherman84

    rancherman84 Senior Member
    Messages: 196

    well i think and was told a/c makes the ford plugs?
    i thought about the IACV also,mine is only noticable at idle also,i dont think it hurts the truck/motor just bothers me! lol