My 04 , 5.4 liter has a "bump" to it only in high gear when fuel is added to go up a big hill or try to pass. It runs smooth through the other gears. Ford had it in there and said it had at least 3 bad coil packs. A mechanic friend of mine said , fuel filter. Coil packs are pricey, Why wouldn't they fail under load in the lower gears? I'm going to change the fuel filter and see what that does.

 

It prolly will...but...you will have to be VERY light on the go pedal.
it has to do with how the PCM see /interprets information from the sensors & and adjusts the spark demand. In those times if you require a light throttle and it starts its "bumb", as you call it......like in a passing situation, or going up a hill.... & you get more agressive with the go pedal, it'll sometimes come out of it.

from your description...it is classic symptoms of bad Coil On Plug (COPs). It is a sign that one or more of your COPs are weak and breaking down internally. thus, not able to deliver that light spark that it requires under those "light throttle" situations.

It certainly won't hurt to change the fuel filter...but I wouldn't hold much hope for long term fix.

the other thing is to check the Fuel Pump Module, near the rear axle, these can also give you flaky runability issues, if the outer housing is deteriorated and moisture then can migrate into the inside

 

Thank you for your quick response. I'll post results when issue is solved.

 

You can get a set of COP's on E-Bay for $75, and most people have had good luck with them. Here's and example.......

http://www.ebay.com/itm/SET-OF-8-IGNITION-COIL-ON-PLUG-FD508-DG511-2004-2011-FORD-LINCOLN-MERCURY-5-4L-/170938429776?pt=Motors_Car_Truck_Parts_Accessories&hash=item27ccb97150&vxp=mtr

 

About COP's---don't try saving a buck on imported or low cost---you'll regret it in the end. There are too many who've cheaped out only to realize in the end its more expensive---this includes me!

On advise from a friend who used Granatelli's in his F150 mine began crapping out about a year later, one at a time until half of them are back to the original pulled parts. Mine seem to hate cold weather, anything below 38* over night and I get the CEL and misfire codes. The rough idle goes away after engine is warmed up and immediately restarted.

Motorcraft brand can be found a lot of places, about $40 or so each. Considering their long life that's not a bad investment.

Do make sure if you pull any COP's out to carefully check the boots---another source of misfires, sometimes incorrectly diagnosed as a bad plug or COP.

HTH

 

Thanks for the info, guys. My truck runs fine unless I add too much fuel in high gear. It is like the key is momentarly turned off. If the fuel demand continues, so does the miss. No enging codes given or check eng light.

 

i had the same exact problem with my 07....the only difference was when it would start jerking i would floor board it and it would jerk worse and i would get a check engine light flash. and it would throw a code for a misfire. at first mine wouldnt do this but over time it did. i replace my coils and plugs and this cleared up the problem

 

Thanks, JJ. That's what I'm going to do, replace all the coil packs and plugs.