Newbie Needs help tuning tranny 2008 G8 GT with Diablosport i3

[G8King]

I just got a 2008 G8 GT after wanting one since they came out. It is red, one owner with 67,500 original miles. Has CAI and axle back exhaust mods. I did the 91 octane tune but am stumped on the tranny. Mostly with the TM feature and adjusting the pressures and rpms for shifts. I have turned off the DOD and don't plan to use it. I have a 4yr/48k miles warranty so I don't plan to do a bunch of mods to it right now. Right now the trans shifts like the clutches are burned out because it slips so much, especially with throttle input(and I have a heavy foot when needed). I tried the Firm shift program with 10% at all intermediate throttle and 20 at all WOT. I left TM on. It felt almost the same as stock. I tried Hard shift and it will bark second gear but it still feels like it is slipping some before it hits hard. Is that the TM function causing that? Can I turn it off and then go back to Firm and make mods? What is the best route? I don't want to feel like it is breaking my neck with regular driving but I don't want it slipping for 2 seconds either. Any help would be appreciated. Thanks.

[5FDP]

You will want to actually adjust the tables manually and not just flash in some random calibration from diablo.

HP Tuners can let you change the tables you want assuming you know what you are doing. The 6L80e can respond really well to custom changes.

[G8King]

I was making the adjustments to the shift pressures and shift rpms manually. I just don't know if disabling Torque Management (TM) will get rid of some of that slippage during gear changes. If it does, then I can go back and start over again in FIRM mode for a less aggressive shift without the slipping. Thanks

[5FDP]

The 6L80e needs the TM to survive and not grenade itself.

I don't know how many tables the diablo stuff gives but HP Tuners can adjust things in pretty fine detail. Like I don't know they let you adjust the on-coming pressure presets which is really helpful in removing transmission slipping or laggyness to the shift. You can even adjust the off-going pressure presets, the shift pressures based on on temp and torque value, TCC settings and shift torque factor. It's always a game you play with the transmission to see what it likes and how it responds to small specific changes.

[G8King]

I understand the basic function of TM is to protect the tranny but I want less slippage in my clutches, which is less heat and less wear. I am not racing the car so I don't think disabling TM will grenade the transmission and I do understand it will put more stress on the driveline and transmission. Keeping that in mind, as I said, if it works like I think it does, it will allow me to get rid of some slipping by turning it off and I will be able to fine tune the firmness manually for each gear and condition. If I was going to do an all out hotrod, I would look at getting HP Tuners to put something together for me that gets rid of the weak stock components in the motor and drivetrain and build me a killer tune. I am at baby steps right now. Thanks for the reply.

[5FDP]

If you can only adjust the shift line pressure/shift times and torque mngt you won't get the desired results.

Leave TM on is about I can tell you. Everything you want done is far easier with this software. Not sure what you expected posting on this forum and asking about a different product.

The 6L80e is nothing like previous 4L60 or 4L80e where people just remove TM without caring, mainly the heavy duty 80e's. The 6 speeds need the TM to complete the shift without damaging it self over time and preventing slamming into gears. I just don't see how removing it will stop the slipping without possibly causing future issues.

[G8King]

thanks for the reply. I posted here because during my research this site was listed as a good resource for the L76 motor and 6L80e transmission. i wasn't aware that this forum was only for those who bought their products/services. Thanks anyway.

[5FDP]

Well when we can't see what you are doing or show you want needs to be changed it's pretty impossible to get an idea of what someone would recommend for changes.

Glad I could help.

[hivoltagedriver]

The Diablosport tuner has VERY limited functionality when it comes to tuning the 6L80. If you want t good transmission tune, get HP Tuners and learn how to use it, or pay someone who knows how to tune it. Having said that, I have fixed a lot of shitty 6L80 tunes from some very "reputable" shops.

And you don't NEED TM on for the 6L80 to survive. I usually leave it on for the downshifts, and depending on the car and owners needs, turn if off or dial it way back on the upshifts. I also disable adaptive shifting when I'm done tuning one. I have done a bunch of 6L80s and 90s, and never had a problem with one that I have tuned.

[G8NOOBIE]

i would agree with both these guys. if you get HP tuners then we can actually help you tune the trans and engine pretty easily