F150 studder under load. 1300rpm exactly.

[Sully]

My 2001 F150 with the 5.4L with 60k on the clock had developed a rough running condition under certain engine load. I had the same problem a few years ago and turned out to be a coil which I replaced and solved problem. It threw a code then though but now it will not. I have replaced plugs and pulled all the coils and bench tested their resistance. Idk what spec is but they were all pretty much right on each other (and the one new one i purchased) except for the one I replace last time which was a tad higher so I replaced it with the new one and saved it in case it wasn't really bad.

Replacing the plugs seemed to hide the problem slightly for a few drives and the new coil might have done the same but it still feels like it misses every once in awhile.

Fyi, i cant do the pull the wire while running thing because it doesn't do it at idle or all the time. Just enough to be irritating and slightly concerning.

I guess next step would be compression test? Just for the hell of it.

Maybe test for a vacuum leak?

Could it be a fuel delivery problem? Not sure when it had the fuel filter replaced if ever so I guess that's on my short list to do.

Would some injector cleaner be worth a try or is that stuff a waste of time?

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[CaptainHenreh]

Sounds like a coil is on its way out. A resistance test will tell you if a coil is bad, but NOT if it is good, you feel me?

[Sully]

Yea. Joe dirt YouTube mechanic said it could so I was hopeful.

I saved the one I took out. I figure it's a coil because it is an identical symptom as the last time it was a coil.

Also, my truck throws a code 0001 or some shit when you pull them and this is the code that tells you that the codes were just all reset and this code is supposed to clear itself after several times of coming up to operating temperature. It's like a warning sign that somebody is trying to hide codes. Well the problem is that the last time the truck was hooked up to a computer and had its codes cleared was 5 years ago when we did the last bad coil. So I'm wondering now if the ecm is stuck in a kind of boot loader (probably a horrible analogy but I'm not a techy) mode where it won't catch new codes.

Regardless if that's the case, I can not get it to throw the misfire code for the bad cylinder so other than replacing random coils one at a time or all 8 of them, I dont know what else to do.

This has been a problem for the last year to year and half probably but the truck only gets about 1,000-2,000 miles in a year now

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[Maengelito]

I vote on coil as well. The problem with coils (and all electronics, really) is that they work until they don't, if you know what I'm saying. If this is truly the problem, it'll appear to work just like a new coil except under load at 1300rpm or whatever you said it was. You also said you already had to replace one. Chances are that more of them are on the way out. If you don't know which one, just get 1 coil, and swap it in. If the problem doesn't go away, move the good coil to the next cylinder until the problem gets better. Or just swap them all out since more will probably fail in the not too distant future.

[PDenbigh]

Definitely a coil. Not a big deal. Those engines are notorious for that, and they are hard to find sometimes. Get the aftermarket Accell brand (yellow) coils. I replaced all 8 of mine on my '01 5.4L around 75k, and didn't have to do it again until around 220k.

They way to find it is to get a good one and start swapping until you find the problem.

Alternative way, if it's really bad, is to unplug one at a time while it's idling, and see which one does NOT affect the idle.

Be sure to use dielectric grease when you replace them, on all connections (spark plug and coil)

Good luck!
Peter

Peter

[.RJ]

I had a similar problem on a different car a long time ago and it turned out to be clogged EGR ports.

[PDenbigh]

It's the coil. High load, low RPM, truck shutters like it's falling apart? Coil. or Coils.

If you're lucky, it'll throw a code that says "Misfire Cyl X" where X is the problem child. Most of the time the coil is still alive enough the ECU doesn't detect it though.

[Sully]

It's the coil. High load, low RPM, truck shutters like it's falling apart? Coil. or Coils.

If you're lucky, it'll throw a code that says "Misfire Cyl X" where X is the problem child. Most of the time the coil is still alive enough the ECU doesn't detect it though.

Yea. It threw a code last time giving me the cylinder in question. Without it though, it's either replace them all or switch them one at a time