allison trans tuning

[dwaller97]

alright so i haven't seen many people talk about this but does anyone know how much to change the torque reduction fuel quantity to remove the defueling of the engine during shifts? i know what table to modify but i dont know how much to modify it to create a smooth quick shift instead of the lazy stock shifting/defueling on shifts. ive seen something about logging desired torque and fuel quantity but i dont know how to make a custom log. any help is appreciated. Thanks guys!

[Dashman]

The stock defuel is about 90% of the actual fuel just before the shift is commanded. I've always figured that when we increase the pulse width it's like making a 60 quantity into a 70 quantity, and now the percentage is closer to 80% and the shifts lag. Work on one shift at a time, scan for RPM, and fuel quantity. Take those values into the torque model to get a torque. Take that torque into the torque management table to get a defuel quantity. Divide the defuel by the actual to get a percentage. On paper increase the defuel quantity, so that your percentage is around 94%. That's what you'd change to in the torque management table. Then you can edit the values around that area accordingly. You may have to edit the torque model, but only when you have complete knowledge of how those tables work together.

[Vlad0380]

alright so i haven't seen many people talk about this but does anyone know how much to change the torque reduction fuel quantity to remove the defueling of the engine during shifts? i know what table to modify but i dont know how much to modify it to create a smooth quick shift instead of the lazy stock shifting/defueling on shifts. ive seen something about logging desired torque and fuel quantity but i dont know how to make a custom log. any help is appreciated. Thanks guys!

Wish i did some Dmaxes with HPT instead of competitor's device so i could give some clear pointers instead of general stuff, like do small changes, some logging, look for bad shifts - 1-2 flare, etc.
I'm not sure that there are universal pointers like "reduce whole table 10% and it will be real good" - every truck's different. Type (lighter's better in this area, 2wd rclb's with rubber carpet have a clear advantage over 4wd 3500 cclb LTZs), condition, mileage, mods. One of the reasons i keep stock tire size and gasser 4.1s on my '04 is to make things easier on 200k + tranny. Downside is 2000rpm@61mph and slightly worse fuel mileage, fulltime awd t-case doesn't help too.

It's real easy to kill Alli with improper tuning; my '04 has stock shift times just because i'm not comfortable with changing them, nor see a reason to do it with stock tranny safe tune.
Tinkering with shift speeds is reasonably safe, defuel takes a lot of trial and error.

Another thing to consider. There is a lot of torque vs lots of weight. Even slightly harsh shifts take their toll on drivetrain, universal joints and other stuff.

[dwaller97]

thanks for the help guys i will be looking into this more before i begin to play with it

[nskyline34]

Any updates on your changes and results?