Updating older 6l80 with newer 6l80 tune?

[mikez71]

My vehicle is a 2012 Tahoe, compared to a 2015 Tahoe and 2018 Silverado tunes.
I'm sure the OS's are different, as I cannot directly compare all maps, but many look similar.

Daily driver, so I'm just looking for it to shift smoothly with less bogging. (3.08 gears)
The updated downshift schedules helped GREATLY. Original tune was waaaay too lazy.
One other thing I used to notice is a rear end/driveline clunk when letting off throttle and it's shifting to 3rd.
Sort of hoping new tune might address this.

Does anyone have suggestions on what to change and what NOT to change?
Here is a list of 'updates' I am testing.
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shift schedule - works fine of course, newer scheduling much better and helping speed up my own tweaks...

CT downshift - modified gradient, possible refinement (2017+)
inertia factor profile - same maps scaled down to 6000 rpm, 1-2 and 2-3 shift had some 8,9 cells replaced with 7. Softening mid-high parts of the shift??
upshift torque adder - same maps scaled to 6000 rpm (instead of 6250). 1-2 and 2-3 look like they have been refined, others exactly the same.
downshift torque adder - similar maps, some more tweaked than others. More changes than the upshift adders.
upshift transition times - similar to stock, some increases, some decreases.

*desired output torque factor!! - 1-2, 2-3 maps have been zero'd! 3-4 was all 0's, now has a ramp. 4-5 got tweaked a little.
*base downshift pressures - significant increase in ONE row, upto 300% over original values, seems to be within operating range, no axis labels.. lessen downshift time?
*adaptive volume and pressure - pressure presets roughly similar. 1-2 and 5-6 volumes were originally ~double the others, those values were halved. Hardware change or compensated by other maps?
torque management cold modifier - seems to have been refined, graph is smoother, just for cold temps
*torque mgt. upshift adder/modifier - had 1's in original adder, now 0, modifier had some lowish negative numbers at low rpm/torque, now zero's...

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Also wondering how much the TCC strategy might affect the shift tuning.
Original tune would sometimes unlock tcc before shifting, whereas the new tunes seem to stay locked during shifts.

OEM 2012 tune 2012Tahoe-T43.original.hpt
'updated' tune 2012Tahoe-TCC123off.15shift.15slip.18inert.18time.hpt
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Update: Drove around the block with all changes. No obvious difference. I've reverted to original for the '*' tagged changes.
For some reason I felt like the new inertia map and torque adder changes may have felt better, so will leave the other changes for now.

Datalog with all changes Log-0032-1GNSKBE0XCR266687.hpl
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Update 2: One thing I found, when using the 15+ TCC apply/release strategy, it would keep the gear engaged despite shift tables saying it should downshift.
(when tcc release was below downshift speed) I incorrectly believed the shift tables would override the TCC setting.
Should be fixed so shifts happen when they are supposed to..

[2xLS1]

Keep the converter unlocked until 5th and 6th gear 50 mph and above. With 3.08 gears you need to take advantage of the torque multiplication an unlocked converter provides. Your TC lock up clutch will last longer too, In my personal 13 GMC Sierra I only lock the converter in 5th at 50 mph and higher and 6th at 60mph and higher and that is with 3.42 gears. You can also add some mph to the part throttle upshift tables especially in gears 1-4 from 0-50% tps. Take advantage of the lower gear ratios in the transmission with the 3.08s.

[mikez71]

Thanks for the tips! I did bump the 0-25% a TINY bit, and mostly blended it to a stock 2015 shift schedule.
Need to get on the highway more for the 5 and 6 tuning. So far they are both about 15mph over the stock tune.

A few issues I don't like when I bump 0-50% too much...
1) slowing and speeding up again, I get the converter slack that needs to catch up. Sometimes going downhill I get that slack as well.
2) occasionally when accelerating REALLY slow, the rpm's can hang a little and then the upshift kicks a little.. or it upshifts and plateau's, requiring more throttle to continue accelerating.

I do a fair amount of city driving, so I do like the feel of lockup in 4th...

The other 'issue' I have noticed in my logs is the skip shift. Now in my stock tune, CAGS disable TPS is 0%. skip shift up and down set to on. Turning off did nothing.
I have logged some skip shifts, that seemed to shift early. I'm not sure if it was my TCC apply settings or what.
Just found a skip shift now, 2-5..15% throttle. Going 43mph.. 4-5 shift is set to 46mph. 5-4 shift is 40mph..
I guess it skip upshifts to the highest gear above downshift speed. Another reason to make downshift speeds high as possible I suppose..

[mikez71]

Here is original (2012) torque adder and inertia tables..
12&34tqinertia2012.gif

Next the 2018 maps..
12&34tqinertia2018.gif

Is shift time a little slower on decels, but faster for accel?
3,4,5,6 maps identical other than the slight RPM header scale.

2012 CT downshift inertia map
CTdownshift2012.gif

2018
CTdownshift2018.gif

[5FDP]

I personally go to around .4500 for shift times at part throttle and go down to .3000 at full throttle. Most shifts end up being around .3500-.4000 with my heavier foot.

Also if it's still on a stock torque converter, it may still be a good idea to have very minimal slip in lockup, I've set mine to 5 rpm now and it usually stays around 0-5 pretty regularly. I'm going to ride out my stock converter and transmission until one of them lets go then I'll replace it with a billet converter that I know can handle more lockup pressure and 0 rpm slip.

[mikez71]

Thanks for the datapoints 5FDP and 2xLS1!

Stock converter.. Still have slip enabled.. figure 20 rpm slip is only one revolution every 3 seconds.
Updating to 15+ slip maps, still commands 20 slip most of the time, but there are dips when the torque is higher, desired slip gets down near 0 and tcc pressure does go up there.
However actual slip is sometimes 10-20rpms, sometimes ~50rpms. 35%-40% throttle in 4th. Pressure around 50psi

I am wondering how the TCC will hold up if I keep engagement speeds low, upto say upto 65% throttle.
Original TCC map looked like a shift map. 15+ TCC map is a flat line.
Little worried keeping it engaged will burn up the clutch at some torque level, as I've heard WOT lock is not recommended on a stock clutch.

Just zero'd the upshift adder and adder modifier table. Used to look like this on my stock 2012 tune.

2012adders.gif

What do negative numbers in the adder modifier do? Guessing they add it to whatever value exists for the torque management.
If so, the original map with negative numbers should lessen the TM on shifts?
For example the torque factor is 1, and on the adder mod map there is a -.1006 at 1750 rpms. Does that mean the factor is now .8994?

[2xLS1]

Go talk to some transmission shops/builders about what is the #1 thing that goes out first on GM 6 speed transmissions.

[mikez71]

I take it you mean the torque converter clutch?

How about 0-50% throttle locked, all lock/unlock speeds and shift speeds higher than stock?
Should be no less reliable than stock I'm hoping.

I hit 40% throttle light/medium cruise (30% accel pedal).

[chevy_man]

Thanks for the datapoints 5FDP and 2xLS1!

Stock converter.. Still have slip enabled.. figure 20 rpm slip is only one revolution every 3 seconds.
Updating to 15+ slip maps, still commands 20 slip most of the time, but there are dips when the torque is higher, desired slip gets down near 0 and tcc pressure does go up there.
However actual slip is sometimes 10-20rpms, sometimes ~50rpms. 35%-40% throttle in 4th. Pressure around 50psi

I am wondering how the TCC will hold up if I keep engagement speeds low, upto say upto 65% throttle.
Original TCC map looked like a shift map. 15+ TCC map is a flat line.
Little worried keeping it engaged will burn up the clutch at some torque level, as I've heard WOT lock is not recommended on a stock clutch.

Just zero'd the upshift adder and adder modifier table. Used to look like this on my stock 2012 tune.

2012adders.gif

What do negative numbers in the adder modifier do? Guessing they add it to whatever value exists for the torque management.
If so, the original map with negative numbers should lessen the TM on shifts?
For example the torque factor is 1, and on the adder mod map there is a -.1006 at 1750 rpms. Does that mean the factor is now .8994?

I believe the stock TC can handle 0 slip, it's just setup to allow slip for "driveability" aka smooth and boring. My older trucks were On/off on the clutch with hydraulic switches and I never lost one. These new converters have amazing material but run stupid programming that abuses them. Leave it to GM to design an incredibly durable part that doesn't last because they only made it durable to abuse it to death.


My stock 6l90 just let go of the converter at 315k in a crew cab long box 7500lb truck. My BIL lost his converter at only 180k in a slightly lighter, but older truck (13 ecsb vs 16 cclb).

I'm looking forward to tuning my own trans once my mvpi gets here. Until I lost my converter I didn't have a clue that GM allowed them to slip constantly.

[mikez71]

Good to hear, though I still haven't zero'd the slip as I'm still tweaking shift schedule!
210k on my 2012 5.3/6l80.

Here's my current tune.. 123TCCoff.2015.shift.noaddmod.inertia.tccslip.2018.TorqAdders.presspreset.tqfactor.ttime-R2.hpt

I imported these 2018 settings for now..
oncoming/offgoing pressure presets, torque adder, transition times, desired output torque factor, adder modifier (zero'd).
Also the inertia profiles and tcc desired slip which are the same as 2015 maps.
I did not use the downshift base pressure map, as there were no axis values to go by.

YOU WERE RIGHT 2xLS1, needed to bump my 5th and 6th more. Not surprised, just going as conservatively as I could.
I do a lot of light cruising and need to be in 5th gear by 45mph.. haven't gotten much chance to get into 6th.

Initial impression, nothing blew up, nothing spectacular. I could be imagining things, but the shifting feels better to me.
I've gone back and forth on tunes, I don't think it's just the torque adder maps.
The trend from 2012->2015->2018 seemed to be lowering some offgoing pressures and bumping some oncoming pressures.
But those are presets and probably adapt.. So then I'm thinking torque output map and transition times..

Regarding the CT downshift, I think the 2018 map may have bumped the factor number. (If 9 is a harder shift and 1 is softer?)
When downshifting I feel the 3-2 and 4-3 more than before. Prefer no bump on coastdown, so I'm reverting back to stock maps.
I wonder why the map can't all be 2's or 3's (if softer than a 5, where I suspect the downshift was happening, changed to 7 in the 2018 map)

How does everyone log nice pressure graphs? Mine are just crude spikes. Interval set to 0ms..

15misc.gif
1st window, looking at the torque adder map, the original map had a valley, which got smoothed/filled in the 2015 and 2018 maps.
2nd window 3-4 output torque scale factor. Was all 0's, has that ramp in 2015 and 2018 tunes. In 2018 tune the 1-2 and 2-3 maps get zero'd.
3rd window 5-6 output torque scale factor. The shape is similar, but values are about 1/2 of original.