I have a 2006 ford F150 FX4 5.4 and I am having a problem with the truck bucking on me, it only happens when I am going about 45 mph or so and 11 to 1200 rpms, or if I am coasting along and go and hit the gas lightly it starts to buck, but as soon as I give it gas it does not do it. Here are the parts I have changed recently, Fuel pump, Fuel pump control module, Fuel filter, throttle positioner, and started to change coil over plugs (cop) done 2 so far, I am not getting any check engine light at all, and hooked up computer and no codes found and no misfires, this is driving me nuts, does anyone have any ideas or ever seen this. Thanks.
im having the same problem with my 07 5.4l. luckily im under warrenty still. i got about 82,000 miles on mine and it does the same excact thing you are talking about. took it in once and they replaced the cat. and the o2 sensors. started doing it again and now i gotta bring it back into ford. i cant stand it, its very annoying. once i bring mine to the delar and they tell me what it is i will let you know what they say and also ill have part numbers if you need.
Symptoms are screaming fuel pump delivery module (FPDM), but I believe you mentioned you replaced it. I would double check the connections and condition there first, as that's one of the first things that will happen when it goes.
Had the same problem with my truck bucking at 45mph for the last 3-4 months. I asked around and figured out that it was the Spark Plugs. My truck is a 2006 5.4L with 89,000 miles. My girlfriends dad changed them for me, and it fixed the problem. He had to buy a special tool to get them out because they are a 3 piece plug and they break off. It will cost a ton if ya take it to a dealer ship because there a pain in the *** to get out. But it definetly sounds like the plugs. hope this helps
plugs aren't too bad but plugs and coils together is pretty expensive. take it to dealer service and they can scan to see if any coils are bad. if not you'll only have to replace the plugs and save alot of $$$. they'll need replacing eventually but its been about 8k miles since i replaced the plugs and no coil issues yet
Definitely spark plugs.. I just went through the same thing with my 06' 5.4 Triton. Maybe run a couple of carbon reducer mixes through your gas tank before you decide to change the plugs. I had no breaks out of 8... I was lucky.