it doesnt do it all the time mostly under accerlation it bucks and losses power act like
its down shifting almost but it jerky, feels like the u-joints are about to be knocked out, change tps sensor ,puzzled?clean fuel filter,serviced trans.checked for vacum leaks,I dont know were to go from here can any one help
I have a 99 f150 w/5.4 under normal conditions the truck will start to buck in overdrive or drive ?
Sounds to me like you have a misfire condition. you need to have someone do a inspection with a scanner and look at mode 6 data for misfires. I bet that I am right.
I have a 99 f150 w/5.4 under normal conditions the truck will start to buck in overdrive or drive ?
I agree with the above poster 100%. It definitely sounds like you have a misfire. For your information, F-150 trucks and Expeditions of that model year range equipped with the 5.4L V8 have been known to have coolant leaking from the heater hose connection the intake manifold metal tube, onto cylinder #4 coil. For an illustration of the concern I'm describing, click on the link below to view an extreme case of exactly what I've described:
http://www.flatratetech.com/forums/index鈥?/a>
I agree with the other posters.. this vehicle has a coil on plug ignition system and are famous for misfiring. the coolant on the number 4 plug was also common this year... but usually it's a coil pack breaking down but not enough to turn on the MIL light on.
Best take it to a dealer who can catch the misfire while driving as most independants don't have the tools to narrow down the issue under load
Also Mode 6 (which is a %26quot;test result page%26quot; of all the tests that are required by the EPA and their results that Ford supplies through a scan tool when requested.. others do supply this page also but not as well as Ford) Doesn't always catch the misfire...
