So Im tinkering around with my tune on my 6L80. I think I finally have the shift times where I want them, working on the firmness of the shift. Ive looked around on here and online, but cant find exactly what the Inertia factor does and the transitional part of the tune? Do you even mess with these? I havent adjusted pressure much, just the TCC apply and regulator a little.
Inertia factor directly references the shift timing tables and honestly should be moved to that area of the tune, but basically it says at this torque input from the engine side and this rpm to use "this" shift cell grouping. So the tcm then uses those shift timing tables for those given points. Hopefully that will simplify it enough to make sense...
If you already have it shifting how you want it, then maybe not worth messing with although it never hurts just to see how it effects things and then whether or not you like it. Inertia settings help to dial in specific shift timings for given engine loads - more load = quicker shift...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
That makes perfect sense. It is shifting really good now. Just ordered a 2800 stall converter and was just seeing what the different settings do. I lowered the numbers slightly in the inertia for the 1-2 and 2-3 shifts. Almost feels like it has a shift kit now. Id love to get the 4-5 and 5-6 to feel like that, like a 4L60 going into OD. Almost like it has another gear lol.Originally Posted by GHuggins
Usually raising the numbers make's them shift quicker. Interesting that lowered them in the lower gears worked out better - I may have to try this on one I do in person later on. I normally change everything using a 6sp tune I built years ago and then go from there. I've basically got grandpa where I didn't mess with any of the downshift or shift inertia stuff and then race where everything was tweaked and will grab 2 gears on downshift with light throttle. I love the 6speeds compared to the 8's - don't think they get enough recognition, but could just be that no one bothers to spend the days dialing them in right.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
I agree about the 6spd. when its tuned right, its alot of fun to drive!
How high can one safely go on the Inertia Factor? All of my stock tables peak at 9, though the software says the range is 0-16. Increasing the numbers as you go up the scale (rpm/torque ratio) has done well with shift feel, but am leary of going over 9. It will still shift plenty firm at 9 on a WOT upshift.
What I would really like to do is get rid of the stepped downshifts where you are in say 5th gear, slam the pedal, and it goes 5-4, then 4-3, then 3-2. 3 shifts at 0.3 sec each does not equal fun.
This sounds like your talking about " Shift Inertia Factor Profile"
If you go to the shift timing tab you can see how these modify the initial shift time and adders as the shift completes.
Honestly, the normal shift time tables are where the majority of the work is done. These tables are meant to trim on top of that. If you notice.. most the tables are only scaled up to 9.. If you want hte profile tables to do more than 0-9 these should be scaled too.
I use the profile tables.. but typicality when I only want a small change in shift time (firmness is how it comes across) . Setting up the main shift times are the best way to go about getting the shift you want.
Tuner at PCMofnc.com
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Yes, the ECM allows for values up to 16. However, the factory calibration only references up to a value of 9. You can see this in Transmission > Shift Timing > Upshift. Look in the Transition Time and Desired Output Torque Factor sections. If you open those tables you will see the column headers only go to 9.
So if you edit the Inertia Factor Profile tables to any value higher than 9, it will be ignored and reference the 9 value in the Shift Timing > Upshift tables. Basically the ECM will ignore values higher than 9.
However. You can use values up to 16, you just have to edit the column headers in Shift Timing > Upshift tables. Click on the underlined text for the column header label that says "Inertia Factor" and now you have the ability to edit this up to a value of 16. The problem is that you only have a fixed number of columns, so you cannot physically define 17 columns (0-16). So if you do this, the ECM will interpolate the values. So as you can see this does not really give the ability to fine tune granularity that you would expect, and there is no real benefit from doing this. So basically I would suggest leaving the inertia factor profiles stock everywhere and just adjust shift timing and pressures to achieve your goals.
As far as Power Down shifts ("where you are in say 5th gear, slam the pedal"), this is how you kill the 6L80E. Never do this. Hold the gas pedal steady and manually downshift using TUTD, then when you are in the correct gear, slam the gas pedal and return the trans back into Drive. Also, every single source of information I have read about tuning 6L80E's says to never alter the factory downshift settings. So my advice is to not try to tune this out...rather, change your driving style and expectations.
As an alternative you can leave it in TUTD and have it automatically shift during WOT pulls in case you forget to put the trans back into Drive. Here is my write up on that:
https://www.ssforums.com/threads/how...e-only.197298/
Last edited by Cringer; 01-19-2023 at 12:02 PM. Reason: i am not a professional typist
Ive gained the firmness I want by adjusting the shift timing via torque adder tables. Put pressure mostly back to stock and ramped up the regulator a little. I have a stock converter for now, but will have a 3000 stall 265mm soon, so hoping that wakes it up some too. With my tune as it is now and with 305/50's on it, it will grab second gear under hard throttle every time. I played around with the Inertia tables some, mostly because under very light torque, it would "glide" into gear, almost like a slip. I actually lowered the Inertia very slightly and lowered shift times across the board.....really helped it.
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