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Thread: 1999 F250 SD 5.4 triton with a miss--and you can hear it on AM radio

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    1999 F250 SD 5.4 triton with a miss--and you can hear it on AM radio

    1999 F250 SD with 5.4 and 5-sp manual.
    With the AM radio on the miss obviously causes static and it's related to engine speed.
    While going down the road with no throttle there's no apparent miss and no static,
    give it some throttle and there's a miss that can be felt plus heard on the radio.

    The truck has 117k miles on it and is pretty new to me.
    I pulled the coil assembly off one of the front plugs but not the plug
    (these tritons seem to have a bad reputation regarding plug threads).
    Is it common for the plug and coil connection to need cleaned?

    What are the first things to start checking? Ignition or injectors?
    Last edited by crabtruck; 04-21-2011 at 08:44 PM. Reason: title

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    Senior Member og25's Avatar
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    Everytime I had a miss on my 2000 f150 it was a bad coil and you felt it under a load, but the engine light would come on. It may take a couple trips before the engine light comes on. You can start by checking the plug boots and see if any of them are bad. Another thought , did you power wash the engine lately? If water got down in one of the plug holes that will cause problems. Good luck!

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    Quote Originally Posted by og25 View Post
    Everytime I had a miss on my 2000 f150 it was a bad coil and you felt it under a load, but the engine light would come on. It may take a couple trips before the engine light comes on. You can start by checking the plug boots and see if any of them are bad. Another thought , did you power wash the engine lately? If water got down in one of the plug holes that will cause problems. Good luck!

    No way would I ever power wash under that hood. No check engine light yet. I did drive it the day before in a very light rain and everything was fine.

    Is there a test for the coils that I can do with a multimeter if I decide to change sparkplugs? Is it common for the contact point of the plug and coil to be compromised?

    Are the Chilton manuals for these trucks any better than the Haynes manuals? I've had Haynes manuals in the past and think they basically
    SUCK.

    Thanks for the reply

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    Senior Member og25's Avatar
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    I personally buy the manufacturer service manual and a chilton's. That is if you plan on keeping the truck awhile. As far as a test I'm not sure. The 1st time a coil went bad on me it was under warranty and the second time the light was on and it told me what cylinder was acting up. I knew from the previous time it was most likely a coil. I don't know if the contact point is a common problem or not. Take the coils off and check the boots for signs of arcing. The plugs are hard to get to , just be careful and take your time. If the plugs have never been changed it's time! Start cheap with plugs and see if that fixes it! Good luck!

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    I pulled a plug and it looked fairly old so I went and bought a set of plugs. I replaced the ones I could get to (5 of them), one of the plugs had some rust on the insulator and connector portion of the plug. The truck ran the same as before.


    I dropped off the truck at the mechanics and he didn't think Bosch plugs were a good idea. There was a GM truck there and boy did it ever look easier to service. I've only had this F250 a short time and have had more trouble than the 94 F150 I got rid of.

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    Senior Member og25's Avatar
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    I sold a 93 f150 when I got my 2000 f150. I had a ton of problems @ 1st , lucky all of it was under warranty. then I didn't have any trouble for a long time. Is the mechanic going to do the rest of the plugs and check it out for you?

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    Quote Originally Posted by og25 View Post
    I sold a 93 f150 when I got my 2000 f150. I had a ton of problems @ 1st , lucky all of it was under warranty. then I didn't have any trouble for a long time. Is the mechanic going to do the rest of the plugs and check it out for you?

    He may even replace the ones I did with motorcraft, not sure at least he wouldn't advise putting bosch in the tougher plug locations. This sure isn't a mechanic friendly engine. I remember changing plugs in a 4.6 car many years ago and it was one of the easiest plug jobs ever. This truck is almost like a mid-engine vehicle. Yuck

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    The earlier 5.4L pulled the threads out of the heads when removing spark plugs, then ford "fixed" it witha new spark plug design and hex size 9/16ths which equaled out to breaking off the plug in the head instead of pulling out the threads. At almost 120K miles you are way overdue if they are the original plugs. Replacing 5 out of 8 is just better than 50%, the same as finding out which is the one that is missing. You just need different length extensions (1.5 inch one is handy) and maybe a swivel and then can get the back ones, They are not easy but they have to be done. The problem with ford even with OBDII is that they can have multiple cylinder misfire and still not set a code or check engine light. I would replace ALL the plugs with good plugs, no need for iridium or anything very pricey since they just last longer, they are not "better". And of course start with the basics air/fuel filter etc... if you don't know when or what maintenance has been done I always assume that it wasn't. If it doesn't miss at idle, just under load then you are most likely looking at losing spark or fuel. i.e. not enough fuel volume (pump/filter/restriction) or low kv/spark not able to jump the gap. Could be worn plugs with too much gap, carbon tracking on the plugs or weak C.O.P. ( coil over plug)

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    I just got the truck back and he put in the remainder of the bosch plugs and found one bad COP. He didn't think the plugs were orginal but they were in pretty bad shape. He also said the fuel rail needs to be removed on one side to change plugs.

    The check engine light never did come on when it was running bad.

  10. #10
    Senior Member og25's Avatar
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    good deal 54, i take it the miss in gone.

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