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4T65E HD Firm Shift Tune

This section of the forum is for discussion relating to the use of the T2 EX tuner/monitor on GM vehicles.

Moderator: sohfast94

Post Thu Jan 02, 2020 9:20 pm

Posts: 1
Hello, I was wondering if someone knew more details as to what is changed for a 2006 Impala SS with the LS4 TCM firm shift tune?

For a few years when it is below 40 degrees out and the car is driven cold, when hitting fourth gear and then coming to a stop I would randomly get a minor rev and then clunk into first. This was on the stock TCM tune. I tried the firm shift tune for the TCM and noticed eventually there was no longer any random rev clunks in to first when cold. I see a lot of talk about line pressure increases for upshifts, but I'm not sure what changes could be applied that would adjust the line pressure for the apply piston. Are pressure increases globally applied? Any ideas what would correct this in the tune, or is it just coincidence I'm no longer experiencing this scenario?

Also could someone clarify if there is torque management disabled for the firm shift tune?


Post Thu Jan 02, 2020 11:11 pm

Posts: 17780
Location: CT

the canned tunes only change shift pressure and how quick it shifts... torque management is NOT changed at all with the preset canned tunes...

for shift point changes, and better adjustments for pressure/firmness and quickness, you'll want/need to get a custom tune done, which I can definitely get you hooked up with...

I had a 2006 LS4 car myself for 8 years, 145,000 miles - a 2006 Monte Carlo SS - and can definitely get you hooked up with more for that car, via a custom tune...

Please send me an email at -- diablo DOT help AT gmail DOT com -- with the year, model, engine of your GM vehicle, any mods done to it, what octane gas you use, which diablo tool you have, etc.. and I can send you a loooong email with info about the custom tuning, the process, etc.

06MonteSS / DiabLew Tune
2014 Camaro SS - 2SS, RS pkg., short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake -- -- --

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