Hi! I was driving my truck the other day and noticed something wierd ('01 F-150) it felt like the gears may have been slipping (i guess). I'd hit the gas and it was slow in picking up speed, and the truck had a slight shake to it. The rpm's seemed ok, and everything was normal when coasting. I hit the highway and the shaking got worse so I just turned around and took it off the road. When i took my truck home that night it drove with no problems, and even when i was driving before it felt like the problem came and went, and sometimes ok and sometimes worse. Any ideas suggestions? Hope i gave enough info.

Thanks
Rod

 

Misfiring under load - probably time for ignition system maintenance if it's not tripping a CEL. Which engine do you have, how many miles, and what's its maintenance history?

 

36,120 with the 4.2 V6. Standard oil changes and had a new computer installed within the past few months because of a previous problem where the engine wasn't starting (got the --------- error message on my odometer), and had a fuel pump replaced.

 

Is the problem absolutely coming from the engine? Is the RPM's deflecting.

Reason I ask , there's a common rear end problem when the fluid/friction modifier breaks down enough it causes a shake and vibration - it can get pretty bad with a LS rear gear.

Generally, the shaking doesn't occur until you've reached 45mph.

Hard to believe you have anything like that happening with that number of miles on her tho.

 

Only 36k miles in almost 7 years? I wonder if the plug wires are breaking down from age........because these symptoms are very similar to what I just had at 82k on my 03, it needed plugs AND wires.

Is it worth 80 bucks to you to get a full dealer diagnosis run on it?

 

It might be if he can't pinpoint were it's coming from. I've had both problems in the past. - Ignition and the rear end. You wouldn't believe how bad that rear end will shake , it feels like the trans is going to blow any minute

Wires - That's a good bet - could be the problem as well. Needs to isolate the problem to the motor if he can.

 

It's not so much of a shake as it is a "lurch". you feel it up front. you hit the gas and the trucks slow in responding, feels like it's slow in getting into and switching gears you know? and it's slow on the acceleration too, and the rpm's look just fine. don't see any change there.

 

What's it do in park? Any symptoms?

Does it rev up like there's not a problem or does it miss a bit? Does it idle smooth?

 

Mine started and idled fine - and ran smooth under light load. Punch it and it would skip like a *****. It also skipped if I revved it in neutral.

 

it doesn't do anything in park. it idles smooth and if you hit the gas it revs up ok as far as i can tell. it's only when driving that it lurches and the engine hesitates when you hit the gas.

 

glc got it right - coils shot or the plug wires are bad - I would replace both or go thru the process of checking all wires - check continuity from one end to the other on each. Inspect the boot and for rust in the plug chambers - it happens .

Your problem is with the ignition system and you will most likely find it when going over the wires.

Good Luck

 

I doubt it's the coil pack - it's more likely wires. If you feel like spending 80 bucks, you can get the dealer to run a full diagnosis.

 

Thank you guys, I appreciate your help.