Im not sure if this is something that can be corrected or not, but if the truck spins the tires at all in first gear it will fly right past the 1-2 shift point and bang the revlimiter hesitate, and then make the shift into second gear. But if the truck has traction this doesnt happen, it always makes a clean 1-2 shift. This is crazy annoying and if there is anything that I can do in the tune, or change in the tranny to solve this I will.

My shiftpoint is around 6200rpms and even if I set the revlimiter at 7000rpms it still does it. And in hp tuners it seems like the only way to change the shift points is to change the WOT shift mph speed, changing the wot rpm shift settings doesnt seem to have any affect on shift rpm?


And what can I do with the line pressures with this tranny? The upshifts are extremely soft at part and full throttle. Id like to firm them up a bit.

 

The 6L80 is definately a different animal compared to the 4L60 when it comes to tuning. Are you using hpt or efilive?

 

hpt, coming from a 4l80 I really dislike this tranny

 

From what I've read there is a lot to be gained in transmission tuning, what are the main things done to make then work si much better?

 

Haha, yeah I am not very impressed with them myself. Have you touched very much of anything in the trans tables besides like rpm shift points? If you would like I could send you a test file with some changes I think you would like as far as shift firmness, etc... and you could just copy and paste the changed tables into your tune and see what you think.

Let me know.

 

That would be greatly appreciated. I think I have pretty much f'ed things up trying to play with it.. haha I really have no buisness messing with the tune. Would you mind looking at my tune file? I could send it to you.

 

Yeah that's fine. Just let me know what you want your shift points at and how firm you want your shifts.

 

I sent you an email, thank you very much!

 

I personally use EFILive, so I can help you but so much. The transmission is awesome. Unfortunately, as usual, it has developed a bad reputation because people don't know how to tune it and they change parameters based upon what they know about 4 speed trans and basically tell the 6L80/90 to self destruct...then get pissed and blame the transmission.

First and foremost, the TCM is VERY intelligent. It has very precise timing and calculations that are made based on the data that is programmed into it. It has parameters and programming that are redundant. In other words, you can't just change a line pressure here and a rev limit there and expect everything to fall into place. Simple minds say "that's stupid". Those who know better recognize that having redundancy in programming is similar to good computer programming....it allows the computer to double check its decisions/strategies/input before making a shift change. The TCM verifies engine speeds, transmission gear, transmission input speed, transmission output speed, and throttle position before determining what gear to choose. With 6 gears to choose from rather than 4, each gear shift BETTER be right. That said you have to become familiar with how the transmission works mechanically before you can just go changing things. Gear engagement and hand offs are not the same as a 4L70/80. Hydraulic pressures and actuations are not the same.

Next, make sure that all the base data is correct. Tire size, gear ratio, et. Look at your ECM's throttle position % numbers and compare them to your actual throttle body throttle position % numbers...make sure the WOT values match.

Lastly, tuning is a science and art...not for the casual enthusiast. That's why the really good guys are expensive and any bloke with the money for a $800 tuner will do it for little of nothing. Familiarize yourself with the trans first. Familiarize yourself with your engine torque band and where each shift will put your engine in its torque curve. Familiarize yourself with the effects of torque converter engagement will be and when you want it to engage/disengage. THEN look at what the base program has each of these settings at in each.