Transmission shifting funny

[Morgoth]

Hi. I have a Diablosport handheld tuner with a custom e-mail tune,similar to blackbear?...My transmission sometimes shift really hard,but it doesn"t do it until the tune has been in the vehicle for a few days....will resetting the TAPS at my allison dealer fix this? My tuner said he didn"t touch the tranny settings...I've done intake modifications that heav yielded 2 mpg better mileage and better throttle response,I wanted to put a semi-mild Raylar cam in it,but not if my tranny is acting up....deep pan,transynd,and full flush doe 25,000 miles ago. Thanks!

[THEFERMANATOR]

Engine tuning controls how the trans shifts, period. Poor engine tuning is the main cause of ALLISON failures in built trannies, and is the primary cause in most all shifting issues. From the sounds of it your tuning sounds like the issue. It sounds like your tuner made changes to the tuning to achieve a crisp shift feel, and the ALLISON TCM is simply learning the tuning and it ends up with a harsh shift after the trans has learned the new tune. The ALLISON isn't like a 4L80E where you can make changes to the engine tuning and the trans just goes with it. The ALLISON has to adapt to the tuning, and once it is done adapting you will know how the tune will shift. It is always a good idea to clear the TAPS when you change tunes though, so give it a shot. Although it sounds like your engine tuning may be your issue.