I have 1999 250 excab powerstroke with supertuner set at tow setting. I get a slight but annoying vibration under no load, hard accereation at low speeds up to about 35-40mph. Any idea where to start looking?

 

I experience a similar vibration. It caused by the torque converter being "locked" creating a load on the engine at that low of a speed. It will go away as the torque converter "unlocks" during additional throttle or just increasing speed slowly to a higher point. I have the older SCMT and it does this on the tow and hp settings.

 

You sure it's not the transmission slipping and shuddering?
Or a stiff universal joint?

 

mine has that after it shifts into OD at 40mph. It does it just enough to notice between 40-45, after that it goes away. It did it before the rebuild too.

 

what is the cause of your vibration?

 

i think its the t/c. If I accelerate hard, there is no vibration at all. BUt since I usually put around like grandpa, i get it. All I have to do is punch it, and it goes away. I've tried additives but its still there. My buds truck does the same exact thing.

 

my 95 does exactly the same thing. i am glad to hear that other have the same thing. i have hoped it wasn't my TC slipping and going south.

back to the post at hand.

i think you are saying that it vibrates from a stop to 40 mph or so. if that is true i would guess a u-joint is going bad. if they are not obviously loose look for rust bleed around the caps (ie the needles are being ground to dust)

 

I've been told we need to shim the driveline. The vibration is caused by the alignment of the driveline being slighty off. I have the part # of the shims if anyone is interested. Thanks to power_stroked7.3

 

Mine does the same thing under no load and puttin' around. Nail the throttle and there is nothin but smooth power... Only when the t/c is about to lock. Did it before the rebuild, does it now as well.

 

Orezona, the shimming was to get rid of the vibration from a dead stop. I went through that. Took new joints, carrier bearing and homemade shim. If chaindog is getting the vibration from a dead stop and it goes away once he gains some speed, I would guess a u-joint is to blame. Stuck ones usually do that.

tjbeggs and powerstrokedlariat- seems like the more people I ask about that little vibration, the more tell me they have it. Really wonder what is causing it.

 

Thanks all I will be start checking things this weekend and report any fixes.

 

Yeah, same here. I get tired of throwing money at it and like my mechanic say's- "If it is something wrong, it will break eventually." gee thanks, I didn't know that...I am just going to deal with it.

 

I also experience a vibration however, mine starts around 40 then goes away at around 45. Not sure what is causing the vibration. It is there even if I coast to slow down.

 

Torque covnerters have a torsional damper inside them that is loaded when the TC clutch is applied. Damper could be bad, or if your shift schedule is not stock, could be engaging the clutch too soon for the damper design.

 

That is the same thing I get and a lot of other people as well.