Ok guys I just bought this truck...alittle back ground on it...highway driven,fully serviced,plugs and cop changed,no codes/lights on...runs great. I am noticing a shake in the driveline somewhere. No its not torque convert shudder, I've had plenty of fords with that. It seems to do it under light acceleration and at lower speeds...if feels exactly like a truck that the carrier bearing is out on but as u know this truck doesn't have one. No noises or clunks. I got under it and it doesn't feel like the u joints have any slack. I am scared it may be internal in the trans but if thats the problem so be it....any help would be appreciated...I did feel of the front yoke and there is very little movement there but some there.

 

Check the coils first. You didn't mention which engine, and the coil problem is mostly with the COPS anyway. Check for any possible pending misfire codes, though you may not see any. Might just have a bad connection on one of them. Without a misfire code, you may end up running resistance testing, or available voltage to each coil.

Dave

 

It's a 5.4......I'm pretty positive its not a missfire but i'll check them anyway

 

Sounds like a tied up u-joint to me id replace them.

 

Yeah, I'm gonna try that first...cheapest thing to try

 

I am just ahead of you with the shaking.

The Ford fleet manager has just finished checking out my 2000 F150 5.4 v8.
He says I need new catalytic converters, three of them for $6000. No.

Here is my history:

Started losing power with shuddering. Forums told me to change cops and plugs. Did that. Got a little better, then a plug blew. Had it helicoiled.

Helicoil mechanic told me to do a valve job $1200. No.

Brought it to Fford for a $90 diagnosis. They said I have a misfire on 5. Changed a new coil for a new coil and it worked. $225 later i was back on the road. It ran great!!!!!! For three days.
Drove 400 miles on saturday like a bandit. Sunday I limped uphill at 15 mph.
Now the truck wont go faster than 25 mph.
It is in the shop for o rings.
They are cheaper than u joints.

Dont be misled. Stay with the ignition.

 

i already did the ujoint and no change of course,lol...i'm gonna buy a cop and swap it to each cylinder to see if the problem changes from cylinder to cylinder...here we go

 

See what happens with all this when few know what they are doing and guess.
Cats, valve job, O rings, coils, plugs, etc.
Plugged/melted cats not performing set a code 420. Did they? They can cause a loss of power if the engine can't breathe.
What codes were set? I did not see any listed.
A faulty coil with 'shorted' turns will cause light throtte stumble and not set a code. Problem is to pick out the cylinder with the bad coil. Even new coils can be faulty or go bad in a short time.
If good diagnostics are done to detect honest issues instead of guessing it saves money and hassle.
Yes Ford cats are about 1700$ +/ each side plus labor. They can be replaced with aftermarket units as long as your not in the state of CA and not use CARB approve parts their..
Watch carefully the condition with mutiple cylinder codes for missfire where the coil primarys are involved. Take a look back toward the PCM for faulty coil switches in the PCM.
I don't have any answers because to many things are going on but to say better work needs to be done here.
There are now two people in the same thread trying to list their troubles.