Valleys In Torque Adder Tables -- What's The Rationale?

[Scrappy]

Y'all,

While following along with various tutorials, I noticed valleys in multiple Torque Adder tables for the stock tune in my '13 Chevrolet Tahoe, as well as in a few other stock trucks with a 6L80. For example, the "Normal" 1-2 table has two different areas that stand out in contrast to neighboring values; I've highlighted one area in blue and another in red. There are similar blue-highlighted valleys in the negative torque region of other tables (2-3, 3-4, etc.), but the red-highlighted valley only exists in the 1-2 table. What is the rationale for this valley?

As an engineer, seeing what looks like aberrant data makes me want to correct it, but I don't want to do so willy-nilly if there's a good reason for it.

Transmission_Shift_Time_Torque_Adder_-_valley_01_highlighted.jpg

Transmission_Shift_Time_Torque_Adder_-_valley_02_2D.jpg

Thanks in advance,
Scrappy

[mikez71]

Hello! I'm also playing with the same years (2012) myself. Here is the Torque adder from a 2018 I believe.
2018ta.png
It's still has the valley, but smoother to the cells around it. I think the resolution of their formula/graph might make parts seem smoother and other parts more extreme.
Also notice the 2015+ map is rescaled and go to 6000rpm instead of 6250.Many of the maps that have identical values have rescaled rpm axis, so it's close enough or was never that precise I suppose.
I feel a handful of the new settings contributes to better shift feel, or maybe because I just changed my motor mounts and reset adapts..

The 2015 tune has a better shift schedule than earlier tunes. (3.08 gears) I have a stock 2012 file that I transcribed with stock 2015 shift tables (maybe tcc and some others as well) for me to use in comparison with stock 2012 files since the format is different... Not sure if 3.42 shift schedules are as different..
2015.shift.hpt

There are a couple spots in the stock 2015 shift map, maybe a glitch, maybe not. Tiny changes that seem out out of place. Not in the shift maps for the 3.42 gears, but for the 3.08.
The peak on the 2-3 shift, which then dips and recovers at the top... and the decimal places dip in the 2-1 shift (highlighted cells). Being TPS % axis, I think it must be mistakes.
2015Glitch1.png

Here is my current tune if you have 3.08 gears..2015.shift.tcc.inertia.coldmod.noaddmod.2018.presspre.tqadder.ttime.desouttq.ctdown.tow.R6.hpt

[Scrappy]

Thanks for sharing those files, mikez71. I'll check out your tune and will let you know my results if I make similar changes. My Tahoe is completely stock and has a 3.08, how about yours? FWIW, three of my four vehicles are modded and I'm solely modding the Tahoe for reliability and driveability.

I hadn't gotten far enough through the various tutorials to run into the TPS vs. speed table, but that looks promising.

[mikez71]

Same, bone stock 5.3, 6l80, 3.08. Didn't think I would mess with the tune beyond disabling AFM, but tweaking the shift points have been well worth the trouble.

[Alvin]

They are doing this just to get the shift feel they want. IMHO they do a bad job of it... well better now days but when 6l80's first came out the programming was terrible and none of the shifts felt very consistent. Some hesitated, some nice.. Putting together a relatively normal shift time table together where it shifts quicker the higher the load is but is constant vs RPM will make them feel more normal. Like you know what your going to get on each shift.

[Scrappy]

They are doing this just to get the shift feel they want. IMHO they do a bad job of it... well better now days but when 6l80's first came out the programming was terrible and none of the shifts felt very consistent. Some hesitated, some nice.

Yeah, I don't like the feel of most of the shifts or the inconsistency.

Putting together a relatively normal shift time table together where it shifts quicker the higher the load is but is constant vs RPM will make them feel more normal.

That sounds like a reasonable approach, thanks.

[mikez71]

Scrappy, my latest tune. The last one I had 4th TCC disengage a little too early causing some flare.
R8b.hpt

To start, I really think you try the 2015 schedule, I'm certain you will like it.
Though I do think the 2-3 needs a small bump at the low end and the 4-3 needs to be more aggressive. (not to mention moving 5th and 6th speeds up)
Overall I think it's a much better starting point.

Here's also the factory tunes for reference in case I screwed up somewhere..

2015 tahoe 2015Tahoe5.3auto.hpt

2018 silverado 2018silverado5.3auto.hpt

[Scrappy]

Scrappy, my latest tune.

Thanks, mikez71!

The TCC disengagement shouldn't lead to any flaring. When you fixed that, what other changes were made at the same time?

[mikez71]

Alvin:
Thank you for the description of a more ideal torque adder table! Looking at all the graphs can be confusing..

Scrappy:
What I had was 4th and 5th TCC disengaging a few mph before downshifting. When the TCC unlocks, the rpms bump up.
I had mine unlocking several mph before and just at too high a speed. I figured it would be safer initially, not really knowing what I'm doing.
In the 2015 tune, the TCC stays locked through downshift.

Other settings I hadn't changed. I have not done any real tuning, or even analyzed datalogs in detail, yet I do believe shift feel is improved due to these following maps.
I have tried more conservative 'updates' with just the shift schedule and torque adder, and somehow it didn't feel as good compared to running the whole enchilada of changes.
Would love to hear your take on it if you ever get to testing these settings out...

shift schedule (less reluctant to downshift, some higher upshift speeds, less bog. No brainer, must try!)
torque adder tables (little bit faster 1-2 and 2-3 shift times, other downshift times also)
? inertia tables
? desired output torque factor (zero'd 1-2, 2-3. 3-4 has a ramp and the 5-6 ramp shrunk in half roughly..)
? adder modifier (zero'd)
? transition times (generally little faster)
? oncoming/offgoing pressure presets (generally higher except some off going pressures are lower)

[Scrappy]

Scrappy:
What I had was 4th and 5th TCC disengaging a few mph before downshifting. When the TCC unlocks, the rpms bump up.

Ah, the RPM bumping up when the TCC disengages isn't "flaring." Flaring is when the oncoming clutch for the next gear isn't engaging quickly enough relative to the disengagement of the clutch for the prior gear, leading to a momentary RPM increase due to both slipping.

[mikez71]

Yes, thanks for the explanation! Thought I may have used the wrong terminology.
The RPM bump was probably drawn out as the downshift was occurring, giving some extra hang time..

Finally got some highway testing today, 6th starting at 66mph, I would frequently slow and drop to 5th.
Going to try starting 6th around 75mph. I have since lowered my 5-4 increases also due to a bump.
Seems like 5th is covering a big spread. from 45 to 75mph..

Will update tune once I dial it in a little. Let me know how your changes/experiences go too!