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Coil packs on V8 and V10's

Discussion in 'Ford Trucks' started by Jerre Heyer, Jul 20, 2003.

  1. Jerre Heyer

    Jerre Heyer Senior Member
    Messages: 948

    Wyldman has probably seen this already but here's a little note for anyone who hasn't.

    We have been seeing intermittent failures on coil packs for the spark plugs on the V8's and V10's. Most just start to run on fewer cylinders but the fun ones are those that run great till the engine gets hot and then start to miss only in certian rpm ranges.

    If you are doing a 100,000 mile spark plug change out or are simply changing the plugs don't forget to check the packs out.

    Driver complaints come after alot of highway crusing and then get off for a fuel fill or stop and the truck runs like a dog. Get out and let it cool down, get back in and it runs fine till the next stop then the same thing happens.

    DTC readers will show intermittent spark failure on the cyl if it is occuring enough.

  2. wyldman

    wyldman Member
    Messages: 3,265

    We have seen a few,but a lot more problems with the spark plug boots leaking.Guys do a tune up and don't apply dielectric grease under the boots,and the leak spark energy down the plug insulator.

    The Check Engine light is pretty quick to come on when you get misfires like that,as the misfire counters will be pegged in no time.
  3. greenquestlawn

    greenquestlawn Senior Member
    Messages: 157

    I guess I may have that problem. Last week after 3 days of rain my truck started missing. Once it dried out it stopped. I was going to get some plugs and wires then I took a look under the hood and thought to my self......."where’s the dang plugs.....and wires......"

    I am pretty quick to jump on maintenance but after reading horror stories online and talking to a few people I do not think I want to tackle this.

    Truck only has 55000 on it, it may have also been bad gas, and I ran premium and some fuel treatment through it as well but hey who knows.

    No engine light though when it was misfiring.
  4. Jerre Heyer

    Jerre Heyer Senior Member
    Messages: 948

    Got nice gooey boots on mine and it starting doing this on the way back from the Symposium in June. Grabbed a tube from the plow prep shelf when I did the plugs about 13K ago. Problem is worse on hot days and long drives but has done it in wet conditions too. Only do 10 miles to work and back so hardly gets hot most days but really sucks when you do a road trip.

    Starting checking with several other shops about it and everyone saw the same type of problem. Mileage loss, and intermittant felt miss. Almost acts like a fuel starvation problem but is no spark.

    Hit the Ford factory computer and showed 3 with 1700-2000 misses and 1 with a 1500-2200 miss. Only did it with the temps elevated. V10 becomes a V6......I thought the V8 was powerless...LOL

    4 new packs and no more problem. Mileage went from 10.5 back upto 15.

    Chris, Thanks for the tip on the grease though. Mine were coated when I took them off So I just recoated them for reinstall. Wouldn't have done that if the were dry coming off. Jerre