Today my Allison tranny would not shift up into the next gear whenever I would accelerate hard or when I would pass and use the passing gear. Only when I would back off on the accelerator would the tranny shift up through its gears. Any ideas on what is happening to my Tranny:(

Diagnosing is tough even with all the info at hand. It becomes impossible not knowing anything.):h INFO please if you want help.:cool:
mike

Here is more explanation. As I take of and press the throttle hard say, to the floor, my truck will start off in first gear and will accelerate untill it is at the end of first gear and hit and stay at the rev limiter but will not go into second until I back off of the pedal abit, it is only then that the truck will go into second gear. The tranny does this for all the gears, second to third and so on.

Any power programs?

no power programs,just stock!

When did you change your fuel filter last?

Last time someone asked me this, it turned out to be fuel filter like Mike L mentioned.

Seems MANY people are missing the 15k intervals. Mine are changed every oil change or 7-8k.

I have a similar problem between 3-4 only. And it only seems to do it for one or two WOT runs. It will just sit in 3rd gear at 3200 for about 2 seconds or more before shifting. Like I said after about two WOT runs through all the gears it fixes itself. I think my problem is because when I drive to work the truck doesn't warm up completely and I only get to hammer it a couple of times a week if that, so my trans adapts to that driving syle. I don't like it but nothing I can do that I am aware of. Maybe a Co-Pilot would be better for my driving style. Anywho, good luck. Keep us posted on and resolutions.

Jason