truck jerking when accelerating above 40 mph
 

I have a 2001 F150XLT 4x4, V8 Triton engine with offroad package that just rolled over 119,000 miles that just started giving me problems 2 weeks ago. When I accelerate at speeds above 40 mph the truck surges or jerks ( the best way i can describe it ) sporadically unitil I get to cruising speed. If I'm cruising at say 70 mph and go to pass some one and accelerate it does it again. The transmission feels like it shifts smoothly thru all the gears and there is no whining sounds, transmission sounds normal. There is no check engine light, so I assume a diagnostic check might not show anything. Advice from guys at work say possible ignition module, coil pack, transfer case ??? It never feels like the truck wants to stall and it never feels sluggish when accelerating like there is a fuel problem. So this being my first time on this forum, can somebody please help ??!! I am somewhat mechanically inclined but my trade is electronics. Any input would be greatly apprreciated, Thanks........

Low-grade misfire.

Yes I agree with project you have a miss, if the get's severe it will set a code and the CEL will come on. A scanner should be able to pinpoint the cylinder, good chance it maybe a COP.

Thanks project and cbradford... your knowledge is greatly appreciated, it seems like when it rains it pours. Had a dead battery not too long ago that left me stranded, had an idling problem and had it fixed, and now this.... third time is a charm !!! And pardon me for my ignorance but what does the acronym COP stand for :-huh Thanks again !!

COP= Coil On Plug

Thanks Chris...

No problem and you have 8 COP's one for each cylinder.

Okay so I did a diagnostic check and found no malfunction codes which we figured would happen since I don't have a CEL and I found where the COP's are on my truck. A couple look like a pain in the rear to get to, and they look diffucult to get out especially with the hard fuel lines over top of them. Is it possible to find out if one of the coils are bad by reading them with an ohm meter ? And is there a good source to get a really good detailed shop service manual for my truck online.

You can pick up a Haynes manual from Autozone / advance auto parts. It tells you everything about the coils how to test and replace.

At 120 k miles you should be considering replacing the spark plugs... its time. When the COPS are off, look at the rubber end over the plug and see if one is swelled 100% oversize. that happens if they get antifreeze or oil exposure long term. That COP you might replace. You can get a full set of 8 on e-bay for $100. and just do all, or do a few and have some for later. IF you play with the truck, stomp on throttle, back off, stomp, etc, eventually you might get a code, then you know which cylinder. In the mean time, i would consider all new plugs.

I've got a 99 with a 4.6 and last year I had a very similar situation as yours. I don't have the COPs on mine, but what it needed was plugs and wires. Runs as good as new. I'm still looking at hitting 90,000 miles on her, but it's gettin' close.

That's the only issue I've had with the truck. I bought it with a tad over 24.000. Knock on wood!!

Thanks for the info....

Hey Steve thanks for the info and the nudging on just going ahead and doing some preventative maintenance. It is definitely time to replace the plugs and if I can get a set of COP's new at a good price then I'll replace them all. Everything you and other responses on here and everything I've read point to the COP's. And thanks for the link for the steps on replacing the COP's , I need all the help I can get !!

Thanks Fordlover55..... words of hope you give me !! By the way, are those mountains behind your truck located in Utah ?