6L80 soft shifts under heavy load

[Estep40511]

So all pressure and volume stock? Only adjust shift timing and torque adder?

[Estep40511]

Heres my tune since I tried Alvins advice. let me know what ya think when you get a chance. Ill try it in the morning.july241.hpt

[Estep40511]

Here is a couple logs from this morning after the changes. It actually feels really good, minus the clunkiness of the stock downshift settings. Ill fix that. Is the 2-6 still slipping? I dont know how to view that in the log on the graph


24-10-05 09-31-33.hpl24-10-05 09-06-55.hpl

[TransGo Robert]

Here is a couple logs from this morning after the changes. It actually feels really good, minus the clunkiness of the stock downshift settings. Ill fix that. Is the 2-6 still slipping? I dont know how to view that in the log on the graph


24-10-05 09-31-33.hpl24-10-05 09-06-55.hpl

Some of the 1-2 shifts are better some are quite worse, mostly the ones under lighter load. But it will take a while to adapt and fine tune the shifts so it might clear up some. It's on borrowed time anyways but if you can get more time out of it by tweaking the tune why not. I use a math channel graph the actual gear ratio so it makes it easier to see what it is doing.

Here's a screenshot of your 1-2 shift under light load, followed by a screenshot of a stock shift in a bone stock engine, transmission, and tune from a 201414 Silverado 5.3L
Rough Light Load 1-2.png
OE Light Load 1-2.png

Now as you can tell the time it takes to make the shift is much shorter in yours because of the changes in the tune and you make more torque then stock, so the comparison is not all that great but it does show you the difference if you look at the bottom yellow trace showing the ratio change you can see what a nice shift looks like vs your bumpy one. You will also notice that were I have the cursor when the shift is finally done in both screenshot, that in yours the commanded solenoid output pressure needs to go about 10 psi higher to finally be able to complete the shift. You have more load then OE as I mention, so it is expected to have to go a tad higher, but that much tells us the 2-6 is struggling quite a bit.

The next two screenshots are under higher load, again first screenshot is your 1-2 shift the second one is from the same stock vehicle as above.
Rough Medium Load 1-2.png
OE Medium Load 1-2.png

In this one you can just how much of a struggle it is to get the 2-6 to clamp down enough to finally complete the shift. The load is much higher so it shows the problem more of course. You can see now that the shifts never gets completed until the computer jacks up the solenoid desired output pressure just after the cursor to 90 psi to solve the problem.

There were no 5-6 shift made under steady throttle, just about all of them happen on lift throttle, so I can't say if the flare 5-6 you said you had at times is corrected or not by the changes you made in the tune.

Last thing, in case you wonder how come the 1-2 is not drastically worse now that your line is commanding to generate only roughly 220 psi while it was set to generate roughly 270 psi before, that's because the 2-6 never get to see full line unlike the other elements in the unit. Also line does very little in those when it comes to shift feel and timing, it only really makes a difference once the shifts are completed for how much load the elements can hold (except for the 2-6 because of what I mentioned). The only way to get full line pressure to the 2-6 is to modify the transmission internally using our TOW&PRO patented technology.

[Estep40511]

I will get another log tomorrow. I upped the oncoming pressure some for the 1-2 and adjusted the inertia just slightly. And made sure the adapts reset. And it gets better the more I drive it. I am adjusting the 2-3 as it shifts super hard. And then I?ll get another log and see if that looks any better. I?ll have the parts next week anyways so I?ll be ready lol. I?ll probably get the kit you guys sell also.

[Estep40511]

I adjusted the 1-2 oncoming pressure slightly, the inertia for the 1-2 and the 5-6. I completely wiped out the adapts this morning at work with my GM scan tool. Test drove it and it seems to shift great. I havent had a chance to get a log yet, but the 1-2 seems better. could just be a band aid. Im going to take out the valve body and check the valves and see if any are sticking. Checked the fluid again this morning and its perfect. So I guess im not convinced the clutches are burnt. lol

[TransGo Robert]

I adjusted the 1-2 oncoming pressure slightly, the inertia for the 1-2 and the 5-6. I completely wiped out the adapts this morning at work with my GM scan tool. Test drove it and it seems to shift great. I havent had a chance to get a log yet, but the 1-2 seems better. could just be a band aid. Im going to take out the valve body and check the valves and see if any are sticking. Checked the fluid again this morning and its perfect. So I guess im not convinced the clutches are burnt. lol

Don't bother checking the valve body, there is only one solenoid and one valve lineup involved in the 1-2 shift, it would be super obvious in the log if there was any kind of valve drag. Also, the computer would notice it looking at pressure switch #3. Those high energy friction plate can take a fair amount of slipping and not burnt, they do drop their coefficient of frictions but if you can compensate in the tune you might be able to avoid going in there for quite a while. I would not call it a bandaid, if you can get it to have a clean 1-2 shift with tuning, it is a fix in my book.

[Estep40511]

Am I correct in adjusting the oncoming pressure preset for the 1-2, since the computer is ramping up pressure to make the shift? I have all the parts sitting here, but you are right. If I can fix it for a while then im fine with that lol

[TransGo Robert]

Am I correct in adjusting the oncoming pressure preset for the 1-2, since the computer is ramping up pressure to make the shift? I have all the parts sitting here, but you are right. If I can fix it for a while then im fine with that lol

I don't know anything about tuning unfortunately so I can't help with that side of things.

[Estep40511]

Heres the latest log. It seems to be shifting quicker and better, but like you said the 1-2 shift isnt a real seat of the pants type feeling. Havent had any flares on the 5-6 shift. And in this log I made sure to leave steady throttle when the shift happens.


24-10-08 12-56-24.hpl

[TransGo Robert]

Heres the latest log. It seems to be shifting quicker and better, but like you said the 1-2 shift isnt a real seat of the pants type feeling. Havent had any flares on the 5-6 shift. And in this log I made sure to leave steady throttle when the shift happens.


24-10-08 12-56-24.hpl

The 5-6 is perfect, the 1-2 is better under medium load, almost perfect. Not much improvement on the 1-2 under very light load, but it probably just needs to adapts. It takes quite a while for the computer to completely fine tune the shifts.

[Estep40511]

I'm not a fan of all the pressure changes.

What happens is the trans will shift faster from the pressure but undershoot shift times because of that.. This drives the adaptives crazy and all of a sudden its pulling shift time/pressure globally (like a long term trim) because sometimes it was too fast. This shows up as randomly shifting super soft / shift flair. The issue can take months to show up.

I'd put back everything to stock other than

*Shift timing Torque adder Normal and special. All else go back to stock
*Downshift torque adder normal and special.

After you do this.. This is going to sound weird. but hit every button in the scanner bi directional controls around shift fast reset, adapt, etc. After you do this the trans will not have forward gears or reverse.. It will be in a neutral stuck state. Then write entire the tcm file. This is the easiest full proof way of clearing all the adaptives..

Give it a few days of driving before making a judgment.


People don't remember this or know this maybe but with 6l80's and HPtuners we got shift schedule, then later got some crude TM settings, then much later shift pressure and inertia factor, then finally all the shift time stuff. We didn't get what you see now all at once. It took a long time for all that to be defined. drip drip drip.

All these things were separated by maybe years. My point is we started tuning them just like the old stuff via TM and pressure. The cars would come back with shift flairs or just not the same as when I left them. Shifts were inconsistent over time. Leaving that stuff mostly if not all stock and adjusting the targeted shift times is where it's at.. I get consistently good results long and short term this way.

I can still get a uncomfortably hard shifts without touching pressures... Even with full TM.

How much should I adjust the torque adder? I saw for a truck to do .35-40 in part throttle. and dont touch anything else? transistion time or oncoming pressures?