hi i have 2008 f250 diesel, i bought it knowing it had a blown engine so i didnt get to drive it before the purchase.
i finally fixed the engine and now i realized that the transmission was acting up which is weird considering i was told that the transmission had been rebuilt a while back before i bought the truck.
it has a hard jerk from 1st to 2nd and 2nd to 3rd and 3rd to 5th and 5th to 6th....the jerking hits harder if you step on the gas pedal more, the worst shift is from 3rd to 5th...
there are no check engine lights and i was wondering if anyone could help me out on here
thanks!

 

does it have the proper fluid level? does the fluid look/smell ok?

 

Yes it has enough oil and doesnt smell or look burned.
I dont know what the problem could be.

 

what kind of mileage is on the truck? To me, it must have been used reasonably hard or had crappy maintenance to have needed both the engine and the transmission to be rebuilt already.

Maybe the transmission needs rebuild #2.

 

Is the truck stock or tuned? If tuned most tunes firm up the shifting in the trans to handle the higher horsepower. Firm shifts are actually better for the transmission...even though it doesn't feel that way. Firm shifts mean less slipping of the clutches on each shift(slipping of the clutches eases the gears into position on each shift).....This makes the shifts silky smooth but also builds heat and wears out your clutch packs faster.

 

It has 140k miles and it has a little aftermarket chip, idk how much power has been added, but whts weird is even when u r driving slowly and not accelrating hard, it stil shufts hard

 

That can cause the harsh shifts. Take it out and see how it shifts.

If that doesn't fix it I think the next step is to get the codes read. The auto parts stores do not have the right tool to read the codes. You need either a Ford dealer or a good independent shop.

 

the chip is some weird thing like it is connected to the obd port and it shows live data and turbo psi levels and how much tq and hp... im assuming it tuned the ecu and even if i take it out, nothing will happen. and i have a maxidas ds708 scan tool. i dont believe any codes showed up for it but i can check again
and i can get u the exact name of the chip/tuner soon and let you know.
thanks for the help so far