PDA

View Full Version : little advice on gently adjusting TCM tune - I want to help not hurt



Boost
June 13th, 2011, 01:27 AM
So I've been researching several of the threads regarding this and learned a few things none of which encourage me too much to go tweaking the Allison settings. I usually leave the tranny tune alone because I feel that if it's not built, the stock tranny really needs the protection of the defuels and such especially to guard it from the 5-600 hp "bolt-on" tunes I've been working with. I always knew I could make it shift "better", at the expense of reliability and possible catastrophic failure. So I haven't. But the defuels get much more noticeable / bothersome on big power applications so if I can "match" the ECM tune better to make the tranny even more reliable and feel smoother, that is what I'd like to do. So what is the basic theory in "matching" the tune, this is a little different than zeroing out shift times and bumping pressures. Thanks a lot!

GMC-2002-Dmax
June 13th, 2011, 11:40 AM
Shift quality has to do with ECM tuning, not TCM tuning. Shift pressure is a mechanical change inside the Allison and not with trans software.

Don't make the mistake and disable the torque request either, that will wreck a transmission in short order.

Good Luck

Boost
June 13th, 2011, 10:35 PM
That's what I suspected, it will be left alone for now. Thank you. The shifts are not bad, just the typical de-fuel in between which is much more noticeable at 500+ horse. Some E.T. I am sure is lost there but I always thought it was worth it and just focus on lauches and power. With a stock tranny I was happy with solid mid 8 second 1/8 miles. It needs to be built for sure not only to "shift quicker" and hold more power, but to be reliable on the long run too. No?

Boost
June 13th, 2011, 10:38 PM
One more thing, if I work towards fine tuning the ECM for smoother shifts, would that be easier on the tranny? Or is a hard defuel very good protection. What areas of the tune are best to start researching about this? Any good threads? Thanks!!

killerbee
June 19th, 2011, 02:30 AM
Not sure which TCM you have? If you have a pre-06, then Tony is correct, and there is improvement in the ECM to be had. Excess defuels (IMO) are an annoyance, especially at low loads. It is possible to make these shifts transparent.

This is not an easy topic to discuss, if centered on refinement and longevity. Except to say that poor refinement, especially in commercial tuners, is simply a lack of any attention to it. You can do much better with a little effort. :)

Boost
June 19th, 2011, 10:46 PM
Sounds good, thanks a lot!