Tuners/gm tech input

M1ck3y · August 7, 2020

Ive read that the 5.3 with the 8spd has different trans tuning then the 6.2. That it actually more closely resembles the calibration for the c7 8spd.

If one were to pay a dealership to flash a calibration designed for a different vehicle on the 6.2 8spd.. Would they do it and would it work?

I'm assuming the 5.3 cal would work even though it has the 3.42 gearing? Also assuming the tuning is different? Would a c7 cal work on the 6.2 8spds?

CamGTP · August 7, 2020

A dealership would never do that, they wouldn't even be able to. You'd be flashing a different VIN/OS into a vehicle that was never designed for it. And it would go against what they are allowed to do anyway.

The only way to make the transmission shift differently would be with a custom tune done by someone or a shop.

This information below is for trucks 2017+, cost breakdown is different for 14-16 model years. (I'm assuming you are talking about your 2017 based on the information given on the post)

It would cost a decent amount of money just to license the vehicle and have the transmission controller unlocked so it could be modified for tuning. Assuming they use HP Tuners the cost before paying someone would be around $600-700 for the license credits and TCM unlock service.

M1ck3y · August 8, 2020

3 hours ago, CamGTP said:

A dealership would never do that, they wouldn't even be able to. You'd be flashing a different VIN/OS into a vehicle that was never designed for it. And it would go against what they are allowed to do anyway.

The only way to make the transmission shift differently would be with a custom tune done by someone or a shop.

This information below is for trucks 2017+, cost breakdown is different for 14-16 model years. (I'm assuming you are talking about your 2017 based on the information given on the post)

It would cost a decent amount of money just to license the vehicle and have the transmission controller unlocked so it could be modified for tuning. Assuming they use HP Tuners the cost before paying someone would be around $600-700 for the license credits and TCM unlock service.

Thanks, had to ask. I didn't realize it was done by vin..

CamGTP · August 8, 2020

Yeah, all calibrations would have to be flashed with a VIN at the dealership and obviously not every VIN has the same operating system/calibration and this is where the problems come.

Aftermarket tuner can take bits and pieces from other calibrations, do a copy/paste and have it be like a different calibration. Of course it may take some time to dial in the right settings and so on but that's how I do it all the time on older computers.

I can take a 4.8/4L60e truck and copy a 6.0 engine calibration into it with a few clicks. Then I can take a heavy duty 2500/3500 transmission information and segment swap the transmission and transmission diag sections straight into the computer if I was swapping to a 4L80e. I would retain the same VIN the truck came with but now I made a combo that was never offered by GM from the factory in a half ton truck.

Edited August 8, 2020 by CamGTP

Darth_Vader · September 2, 2020

If the TCM isn't locked and the part number for the TCM is the same for both you can write the config from the Corvette to it, but it probably wouldn't be as a good an actual tune give how Torque is utilized to control transmission parameters.

lucas287 · September 2, 2020

I've spent a considerable amount of timing tuning the calibration on my 8L90. I've compared it to Corvette files, Denali files, Sierra, Yukon, etc.. Pretty much all the truck-based stuff is the same.

The Corvette calibration is entirely different. The TCC lockup schedule is more intuitive than the truck-based schedule. Also, the shift scheduling is more performance-oriented instead of lugging like the trucks. Shift times are much quicker in the high torque/rpm areas. Even the TCC desired slip tables are different.

All in all, yeah the trans tune was pretty much garbage from GM. Between changes I've made to the trans side and some minor changes to the engine side, it drives a lot better.

But yeah, what @CamGTP said is spot on. No dealer will ever do that. And the cost for you to make changes to your '17 is a bit steep. @WS6FirebirdTA00 has a 2017 with an 8 speed so maybe he can advise on what the process is.

WS6FirebirdTA00 · September 3, 2020

Yes it sucks for sure!

It cost me $800 to tune my own truck and I already had the hardware.

$200 TCM

$200 TCM unlock

$200 TCM license

$200 ECM license

Ouch!

What are you trying to change the calibration for? Any specific issue?

M1ck3y · September 5, 2020

Just the usual. 1-2, 3-2, or is it 3-1? But I had read something like lucas287 just stated, so I was curious if there was a cheaper way to get better functional performance out of the 8spd.

There should have been two stickers when I bought my truck.

WARNING: Drives like ****** so it will meet emissions...

WS6FirebirdTA00 · September 5, 2020

42 minutes ago, M1ck3y said:

Just the usual. 1-2, 3-2, or is it 3-1? But I had read something like lucas287 just stated, so I was curious if there was a cheaper way to get better functional performance out of the 8spd.

There should have been two stickers when I bought my truck.

WARNING: Drives like ****** so it will meet emissions...

Just go for it and make the investment. It is well worth it. While I can catch mine from time to time in an odd state, maybe 1-2x per month, it feels great otherwise. I really look forward to driving the truck.

The odd spots can be there in just about anything depending on what you do during an active shift. Downshifts are still slow if it is actively in the middle of another downshift.

The other day it actually barked tires shifting down to first on a slow roll WOT kick - I actually backed out a bit to stop it. That put a smirk on my face, but I dialed it back a little lol

Mine took a lot of tweaking the driver demand, torque converter apply pressure, shift speeds, inertia, shift timing, etc. - you have to be patient with the adaptation this transmission does. You can overcorrect if you aren’t patient. I was also slowing down tuning as Gen 4 stuff was ramping up (cut my teeth on Gen 3) so the Gen 5 stuff just took me a while to learn (and still am).

Showroom new, the factory calibration sucked SO bad off the line. Traction off it would not even attempt to roll the tires over. It felt in 4 cyl mode. After tweaking the traction actually does it’s job to limit wheel spin to get out of the hole strong.

I disabled DOD and have had a best real MPG of 22.3 on a country road cruise. By the way, you can recalibrate that too - factory mine was was high on the DIC. My best half tank of gas - which is where I normally fill up - was 20.7 MPG calculated using the same pump and topoff method. That was driving mostly country back roads from 25 MPH to 55 MPH. I haven’t had any long highway cruises to see straight highway MPG.

I say all that to tell you this, a good tune on these trucks make them a lot of fun. I actually used my tow haul button to hold gears out for towing, but since I never really tow I favored it towards a “sport mode”. Real easy downshifts and delayed upshifts vs TPS.

Edited September 5, 2020 by WS6FirebirdTA00

tyler.frost92 · September 9, 2020

Anyone care to share some HPT files for comparison? Trying to understand this gen 5 stuff is pretty confusing. Just got hpt and have only changed a few PE settings, tire size, disabled DOD, adjusted idle, fans, and stuff like that. Hesitant to adjust anything power wise without more studying. My truck is a 6.2/8 speed if anyone cares to share some info.

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WS6FirebirdTA00 · September 11, 2020

PM me your email

lucas287 · September 19, 2020

On 9/9/2020 at 6:57 AM, tyler.frost92 said:

Anyone care to share some HPT files for comparison? Trying to understand this gen 5 stuff is pretty confusing. Just got hpt and have only changed a few PE settings, tire size, disabled DOD, adjusted idle, fans, and stuff like that. Hesitant to adjust anything power wise without more studying. My truck is a 6.2/8 speed if anyone cares to share some info.

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I'd be happy to share my latest calibration too. Literally haven't touched spark or fueling at all. I've tried many variations of cam timing too, but I'll just share a tune that's basically stock except Driver demand, DFCO, PE, and lots of trans changes.

I actually have had great success in LOWERING the values in the Driver demand table. I left the top row alone to ensure I would get 100% pedal when I want it, but the rest has been greatly reduced. On the stock settings it was just far too aggressive and jumpy. I didn't mind it because it felt real torquey! But it got old quick because it was unpredictable and not very smooth. I studied up on the Corvette driver demand tables and started with just copy and pasting right over. The result was very nice, but it was a bit too subdued! Since then I've finessed it and I think it's almost perfect now. You can easily modulate the throttle and with DFCO completely disabled it makes for very smooth transitions.

On the trans side, I keep the TC completely unlocked until 6th gear, so right around 30 mph. I also tried many many combos of shift scheduling and found that I just like the stock schedule the most. I dont think it was ever the problem. I think the goofy lockup schedule, jumpy driver demand, and aggressive DFCO made it so clunky and awkward as you transition from accelerate to coast to accelerate.

I really look forward to dialing in my MAF tables and VE because I'm sure it'll get EVEN better.

Didn't mean to type all that, I'm just excited that you're getting to make significant changes in driveability and want to share what's worked for me.

tyler.frost92 · September 19, 2020

I'd be happy to share my latest calibration too. Literally haven't touched spark or fueling at all. I've tried many variations of cam timing too, but I'll just share a tune that's basically stock except Driver demand, DFCO, PE, and lots of trans changes.

I actually have had great success in LOWERING the values in the Driver demand table. I left the top row alone to ensure I would get 100% pedal when I want it, but the rest has been greatly reduced. On the stock settings it was just far too aggressive and jumpy. I didn't mind it because it felt real torquey! But it got old quick because it was unpredictable and not very smooth. I studied up on the Corvette driver demand tables and started with just copy and pasting right over. The result was very nice, but it was a bit too subdued! Since then I've finessed it and I think it's almost perfect now. You can easily modulate the throttle and with DFCO completely disabled it makes for very smooth transitions.

On the trans side, I keep the TC completely unlocked until 6th gear, so right around 30 mph. I also tried many many combos of shift scheduling and found that I just like the stock schedule the most. I dont think it was ever the problem. I think the goofy lockup schedule, jumpy driver demand, and aggressive DFCO made it so clunky and awkward as you transition from accelerate to coast to accelerate.

I really look forward to dialing in my MAF tables and VE because I'm sure it'll get EVEN better.

Didn't mean to type all that, I'm just excited that you're getting to make significant changes in driveability and want to share what's worked for me.

I'd be interested in checking that out. I've been studying alot of stock files, modified files. And have actually started logging and sending files back and forth to a tuner. So far it looks like most of the changes he's made have been in the base spark maps, PE, DD, and VE. I haven't got the the TCM unlocked yet but that's what I'm most excited for. Klug Performance has my truck feeling pretty good after 1 base map and 2 updates since logging. If you want to email me anything my email is [email protected]

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