I just started to develope this after my latest CEL that has gone away (P0455). While cruising the truck starts to develope a vibration, nothing rough but kinda annoying. It only does it when actually accelerating or on the throttle. If let off the throttle to coast it stops. Its led me to think its either 1. U-joints 2. Tranny needs to be flushed. Im thinking its the latter of the 2. I have no idea when the last time it was flushed before i bought it in september with 113k on it. What other things could be causing this vibration?

 

I'd have to guess a coil pack is starting to get bad. This is the most trouble prone part of the truck to cause those symtoms. Once it gets bad enough you'll get another CEL.

 

well if thats the case then i'll be ordering my ignition setup sooner then i thought with efans.

 

My old 2002 Ford Explorer Sport had a similar problem, only it did that while coasting 20mph threw residential neighborhoods and so on, didn't experience it accelerating. But I think its your transmission

 

i'll do everthing then. I'll have the tranny flushed next week when i get paid.

 

It does sound like a light misfire as already noted.

Fortunately, a decent scan tool (not a basic code reader) can go in and look at misfire counts so you don't have to guess and just throw stuff at the truck and see what sticks.

Steve

 

autozone wouldn't be able to detect misfire counts would they? I dont have the ability to get one of those bigger scan tools that can detect everything.

I've wanted to replace the coil packs/plugs and wires anyway. But if its not that then i dont want to throw money away right now. MPG have gone back down again, had gone up untill this last cel and vibration.

 

Your P0455 was an emissions evap fault that cleared. It has nothing to do with a miss.
IMO you will be throwing money away at this time buying coils until there is positive proof that the roughness is caused by them.
I would be looking first at the U joints. They will act as you are experiencing under load and when load is relieved.
I just went thru this and all jounts were bad at 150k + miles.
Spend your money where the problems are and be happier.
If it's transmission shudder then you will be thinking of repair on it.
The other possibility is plugs. When cruising, the EGR opens, cuts fuel and advances the timing. Sometimes the plugs won't fire reliably when the fuel is lean at that time.

 

good thing i still have that 1 ujoint still. Should've had it installed when i did my tires and shocks. But i'll have it put in next week.

As for the tranny, i dont know if the previous owner ever had it flushed so it wouldn't hurt to do anyway. Aswell as the ignition.