8L90 Tuning Success and Suggestions - Full Size Trucks

[dc11704]

Has anyone had success with their tuning for the 8L90 in the 2015-2020 GM trucks? If so are you willing to share details of your results and your tune file? I have been going through and have decided on the DOD Disable and omitting TCC lockup in the lower gears, but I have heard mixed things about people playing with pressure changes and temperature compensation and I am wondering if anyone has firsthand experience (good or bad) with these changes and what they would recommend. Any advise is appreciated. I am tuning my 2015 Escalade with the 6.2 and 8L90 with around 75k miles on it...

[Tfoggy]

Following this post.. I've done the 6L80E's but really not much with the 8 speed. My son wants me to tune his 2016 Yukon Denali, so
I'd be interested too !

[Ben Charles]

A lot of the trans tuning to be honest is from the engine side with tq model to be honest… naturally things can be changed on TCM side with pressures and what not, but VT can make or break the shifting

[GHuggins]

Would have to agree with Ben. I personally have one trans tune for the 8speeds - funny enough was developed in a picky owner's escalade - that I will fine tune via the customers wants for pressure and shift settings. It has pretty much all of the tm disabled - yep works best in my opinion on these - and then I adjust the torque model for preferred shifting characteristics such as quick response downshifts and for shift pressures in all of the 8sp truck and cars I tune. You have to start by taking a lot of shift pressure out of the trans cal when you kill tm - you can use 6sp cals as a rough guess, but as long as you don't take too much out you can then use the torque model for tuning it to perfection if you like.

Airmass adjust line hold pressure and shift pressure
Map adjust shift effort - in other words how much pedal it takes to command a shift / map will also tweak shift pressure, but that's primarily done on the airmass side - lower settings means easier to downshift

You also need to keep torque positive at idle - if you get to adjusting that area - and positive just off idle, otherwise you can wind up slipping R clutches just to start with.

[Alvin]

Has anyone had success with their tuning for the 8L90 in the 2015-2020 GM trucks? If so are you willing to share details of your results and your tune file? I have been going through and have decided on the DOD Disable and omitting TCC lockup in the lower gears, but I have heard mixed things about people playing with pressure changes and temperature compensation and I am wondering if anyone has firsthand experience (good or bad) with these changes and what they would recommend. Any advise is appreciated. I am tuning my 2015 Escalade with the 6.2 and 8L90 with around 75k miles on it...

I treat them largely like the 6l's.

I don't up the pressure. I do spend a lot of time setting the desired shift time (with all its adders) to something that is comfortable at lower throttle and more aggressive at wide open.

I also leave most of the TM in it.

The shift pattern is where a lot is to be gained. I've got an excel calculator I built a really long time ago but the Bluecat software seems popular. I don't know if it will work on 8 speeds. Fixing the shift pattern will make a huge difference even with the stock shift firmness.

Lately I've been delaying the higher gears until it's at a range where the TCC can lock and stay locked. Surprisingly very comfortable.

If it's got the TCC shudder or an aftermarket converter I'll edit or zero the desired TCC slip tables and give it more pressure right off the bat to lock up.

[TheMechanic]

I treat them largely like the 6l's.

I don't up the pressure. I do spend a lot of time setting the desired shift time (with all its adders) to something that is comfortable at lower throttle and more aggressive at wide open.

I also leave most of the TM in it.

The shift pattern is where a lot is to be gained. I've got an excel calculator I built a really long time ago but the Bluecat software seems popular. I don't know if it will work on 8 speeds. Fixing the shift pattern will make a huge difference even with the stock shift firmness.

Lately I've been delaying the higher gears until it's at a range where the TCC can lock and stay locked. Surprisingly very comfortable.

If it's got the TCC shudder or an aftermarket converter I'll edit or zero the desired TCC slip tables and give it more pressure right off the bat to lock up.

Bluecat doesn't do the 8 speed. Even the latest versions are kinda finicky because of the changes in HP tuner software. Not just a copy past any more. I wouldn't mind seeing that excel file though. I think I have a few 8 tunes I will try to post when I get off work

[JoshC]

I treat them largely like the 6l's.

I don't up the pressure. I do spend a lot of time setting the desired shift time (with all its adders) to something that is comfortable at lower throttle and more aggressive at wide open.

I also leave most of the TM in it.

The shift pattern is where a lot is to be gained. I've got an excel calculator I built a really long time ago but the Bluecat software seems popular. I don't know if it will work on 8 speeds. Fixing the shift pattern will make a huge difference even with the stock shift firmness.

Lately I've been delaying the higher gears until it's at a range where the TCC can lock and stay locked. Surprisingly very comfortable.

If it's got the TCC shudder or an aftermarket converter I'll edit or zero the desired TCC slip tables and give it more pressure right off the bat to lock up.

When you zero the tables are you zeroing the "AC Off 1st - 8th" tables under "TCC desired slip"? I have DoD disabled so I wouldn't think I need to mess with those tables.

Screenshot 2023-03-03 at 10.03.58 AM.png

[04silverado6.0]

I treat them largely like the 6l's.

I don't up the pressure. I do spend a lot of time setting the desired shift time (with all its adders) to something that is comfortable at lower throttle and more aggressive at wide open.

I also leave most of the TM in it.

The shift pattern is where a lot is to be gained. I've got an excel calculator I built a really long time ago but the Bluecat software seems popular. I don't know if it will work on 8 speeds. Fixing the shift pattern will make a huge difference even with the stock shift firmness.

Lately I've been delaying the higher gears until it's at a range where the TCC can lock and stay locked. Surprisingly very comfortable.

If it's got the TCC shudder or an aftermarket converter I'll edit or zero the desired TCC slip tables and give it more pressure right off the bat to lock up.

Would you be willing to share this excel calculator?

[Alvin]

I'm sorry. Probably not. Hard to say this without sounding too high and mighty but I'm a professional at this and this tool I created gives me an advantage over the competition. Hard to justify sharing it.

I will say it is heavily influenced by Bluecats stuff. I even wrote him a email telling him how much I appreciated his approach cause I've been struggling describing what I want with math.


A long time ago I shared a Cam calculator that will figure out P2V pretty damn exactly. I still get "tech" phone and email calls about that. Sorta learned a lesson.. you can put together something really nice and someone who has no business using it will expect you to hold their hand so you can basically do it all for them.

[04silverado6.0]

I developed a new tunerlock bypass method for p01/p59 that can be done in 10 minutes or less, hptuners only, no soldering and doesnt loose the calibration. No keys needed. May be able to make a trade if you send me a message. I also have a advantage over others but it is right under their nose.