I have a 1999 ford expedition w/150000+ miles. My problem is that when try to accelerate the engine seems to hesitate or start jerking. The engine runs good at idle and in drive. At the same time I also had P0171/P0174 codes which turned out to be pcv hose had a hole in it. I replaced the hose and the codes cleared but the engine still jerks. It usually smooths out as I speed up.Could it be the DPFE sensor? I replaced the spack plugs/wires earlier this year or late last year and the throttle body seem to be clean visually.

 

Sounds weird, but check your tires. Mine gets a little wear difference from front to rear and the computer tries to compensate and creates a jerk under load- also does it going up hills pushing it.

 

what brand plugs and wires? and did you use dielectric grease inside the wires?

 

Mine is doing the same thing! It has about 140k miles so I hate a ton of money on maintenance when I'm looking for a new car. I feel like it's the Plug Coils but I honestly don't have a clue. Anybody know about how much it will cost to replace the coils & plugs?

 

you should wait till your at cruising speed to start jerkin

 

Bad plug or coil will throw a code. If a coil is bad and it starts to jerk, my check engine light flashes at me like "hey you- get a coil!!"

 

Bad plugs and wires have been known to NOT show a CEL. Yea, if the miss is bad enough, the CEL will flash. I have seen it not though, and, the plugs and coils/wires being replaced will fix it.

There still may be a pending code to be read... I would get it read again...

 

That's for all the help. I had it looked out by a FORD mechanic and he pointed out to me little white marks on my wires. He told me that it was my spark plug wires were arching and needed to be replaced. I took his advice and replaced the wires and it fixed my problem. I also remembered that I had a lifetime warranty on my wires, so I got a new set for free.

 

Just need to stop buying cheap parts. Working as a service advisor in Ford dealers for the past 11+ years, I have seen alot of parts store brand parts hose up vehicles. Buy GOOD wires, Motorcraft plugs (please, oh please, no Bosch) and coils. I know that it sounds like I am trying to push the Ford stuff; but, trust me, it works better-longer.

 

I have a 99 Ford F150 4.6, when I accelerate at about 30 and up my truck starts jerking. There are no engine codes. Plugs, wires, and packs are new. Fuel system is all new. I just can't figure it out. PLEASE HELP!!!

 

The old torque converter mechanical lockup slipping could be your problem. it was a common issue with the older 4R70Ws. I had the issue with my 95 Mark VIII Lincoln. A trans fluid change fixed it. It happened when I accelerated slowly at low speeds and felt like the car was going over some railroad tracks.

 

Why did you post in a thread that's 7 years old in the Expedition forum? Please start a new thread in the correct forum. Thank you.