Hey guys! So I've been a member here for a bit but never active, just reading various articles here and there. I know that others have posted about this topic, but I haven't quite yet found the answer I've been looking for. I've got an 07 5.4 that has been giving me some trouble on the road. When on the highway and particularly in overdrive it starts to buck when a light load is placed on the engine going up hill or accelerating downhill and remaining in overdrive. If I accelerate enough to get out of overdrive, the bucking goes away.
This happened a few years ago bad enough to throw a code, and I found that one of the coils had gone bad, I replaced it and problem was fixed. This was around 90k miles and on original plugs and coils. Shortly after I replaced the plugs with Motorcraft plugs (what a headache, but glad I saved myself the $800 shop bill) at 95k miles. About 6 months ago the jerking slowly started to show itself again but would not get bad enough to throw code and tell me what cylinder it was. I went ahead and purchased 8 new $40 coils on amazon (what a mistake that was). They fixed the problem for about 2 months and the jerking came back and got pretty bad. I figured it was those cheap coils and invested in 8 new Accel coils. That seemed to fix it for a couple months but now the jerking is coming back.


I know that the Accel coils are supposed to be great replacements compared to Motorcraft ones, and at half the cost. My question is do you guys think it could be that I have bad luck with coils, or that my truck keeps making them go out? Im at 125k miles now. Do you think I could possibly replace my plugs because one or two have gone bad? I would pull them and look at them, but I'd rather spare myself the headache of possibly breaking them.


So replace all plugs or just keep replacing coils that temporarily fixes the issue? And if I replace the plugs I've seen that the Motorcraft SP-515 are supposed to be good especially when paired with Accel coils. I would take it to a shop for them to try and fix it, but this is something I could do on a weekend and I do not trust any local shops because they are known to rip off military. Thanks guys!

 

You said it only happens in high gear? have you tried resetting the computer by unplugging your battery? also, may be worth letting your engine throw another code.

 

Some have luck with Accels, some do not. Did you put motorcraft plugs in it? That is a must.
I had the same issue with the bucking at light load. I cleaned my MAF and throttle body, and it has never done it since. Also doesn't hurt to throw a fuel filter in it.

 

To the best of my knowledge they are. I planned on replacing the filter and cleaning the MAF, I took a look at it today and it did have a bit of build up on it. I would also wait for it to throw a code but it took a couple of months to do it the first time, and I don't want to deal with this for that long.
I'm thinking a new set of plugs and a tune up should do it. We shall see!

 

Do you have anything like a cold air intake, or aftermarket drop in air filter?

 

Yea I have a k&n cold air

 

Cheap COP's can and will cause a good plug to go bad...this may of happened to you with the $40 set you installed..if you replaced the plugs with Motorcraft SP515 plugs they will come right out now.. new design should not break. I would remove and replace all 8 again and install new boots and springs. as for COP's it's a crap shoot...the Accel's should be fine. I would also check the condition of your FPDM located under your spare tire..normally corroded to the frame rail.. this too could be the culprit of your bucking under load.

 

Clean your MAF and throttle body.

 

Bad coils will eventually damage your cats as well. If acting up in high gear, try taking out of overdrive when it acts up, may be a trans issue.

 

Cats were replaced a year ago, boy did that take a chunk out of the wallet