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When tuned, my 06 6.0 doesn't shift very well. I took it to a shop, they said it needed a new tranny, put a new tranny in and it has the same issues. I've tried sct tunes and innovative tunes and the truck still has issues. Sometime when shifting, it has a slight hesitation then a hard shift. Sometimes I'll go 0-60 at maybe 3/4 throttle and when I hit 60, let off the throttle, it'll stay in 3rd or 4th gear at around 2,800 rpm. After replacing the tranny and putting different tunes on it, I would assume it has to be a sensor somewhere that is not giving it the correct information?
 

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The trans uses vehicle speed and pedal position as the main inputs. There are many others that can modify the shift schedule, but those are the main ones. If you replace both of these I'll bet you will still have the same problems.

You need to find a shop that knows how to diagnose problems, not just change expen$ive parts like transmissions. Was the computer commanding the trans to shift and it wasn't shifting? Was the computer not commanding the shift? What do the input signals look like? These are the questions that need to be answered to be able to diagnose what's happening. A good tech with the right scan tool can find these answers in a two mile test drive.

If it shifts badly with the tunes, but shifts right with the tunes removed from the vehicle, then the problem is the tunes, not any sensor or the transmission.
 

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I had very similar issues with my 05 F250 6.0 CCSB. I installed upgraded EPC solenoid and direct drive solenoid along with new filters and the correct Motorcraft mercon SP. ordered solenoids from MTS. All the major problems were fixed but still didn't like the way it shifted so I ordered custom tunes from WPE and trashed my innovative tunes. It's like driving a totally different truck. Good luck.
 
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