2017 Tahoe 5.3 6L80 Tune for Longevity - Can I do it?

[Fast4.7]

Exactly my reasoning as well Fast4.7! (California heat and traffic)
I seem to hit 180deg trans temp pretty regularly/easily.

There is a particular instance where I think lockup in 2nd would help.

Going down a steep street at a local park, I brake to slow my speed.. near the bottom I want to nudge the gas a little bit.
But the coasting outruns the converter, so there is a bit of slack before engaging..
(probably 2nd gear) For that situation, I guess locking in 2nd would help..

I could see conditions for a 2nd gear lockup. That is what Nissan does on the 7spd I had in my 2011 M56S and my mom's 2019 Titan has. Partial lockup in gears 2-7 and full lockup in 7th from memory. I did find the lockup noticeably more annoying than the older 5spd that only partial locked in 4th and 5th and full locked in 5th in the Sedans like my 2007 G35 Sedan and in trucks/suvs locked partial in 3rd and full locked in 4th and 5th like my Pathfinder and the 2012 and 2014 Titans I had. The TCC was always locked too early in 5th regardless of the vehicle or engine and it would lug them down to ~1,000 rpm causing a mild TCC shudder. The G35 had the worst 5th gear shudder as that VQ35HR really wanted to run in its 3,000-7,500 rpm powerband. The newer stuff definitely had better fuel mileage but there was more to that than lockup strategy or added transmission gears alone. Higher compression ratios, Direct Injection, VVEL on the intake cams and exhaust cam phasing were also added to the newer V8 engines compared to the older ones.

[TEDDY J 50]

If I only change the TCC so it won't come on in 2,3,4 can it be written to the program or do you have to load the entire transmission program or will only the changes I make to the TCC portion be applied and do not have to worry about the rest of the program.

[mikez71]

It's going to load the whole program, so make sure the whole (tcm) program is the write one!

[TheDoofus]

Thank you TheDoofus!!!

No Problem! Glad it was / is helpful.

I wanted to check back into this thread after driving the Tahoe for about a month with the TCC / DFM changes to update on my observations. Note I still haven't made the slip changes yet, as I wanted to test each change in isolation.

Here are my observations so far on the "no TCC lock in 1-4":

Negatives:
1. It combined with the DFM / AFM delete does seem to eat into fuel economy reducing it by about 25% around town (only about 5% on the highway).
2. There is some "slack" in going on / off the throttle that I can notice, especially in 2-4. Though I will say that my wife told me she doesn't notice anything different about it ... so I might be noticing it because I expect to notice it.
3. It does generate some heat around town, though with the thermostat delete, it never gets above 150 even when it was 90 degrees out.
4. I don't have much engine breaking (if any) especially in first even if I have tow haul mode engaged. I admit I don't understand much about the TC mechanics when it comes to this and I haven't taken any logs yet (need to do that this weekend) to see what exactly it is doing here (is it actually dropping to 2nd, or is it really holding first?). I do enjoy having a bit of engine breaking, especially in heavy traffic, but it may be the price I have to pay for not locking the TCC.

Positives:
1. It shifts very smooth.
2. It "hunts" a lot less for gears. I have lots of smaller hills here and the slack gives it a chance to apply a bit more power before it wants to down shift.
3. No random hard shifts. I didn't get these frequently anyways, but every now and then seems like it would shift while having the TCC locked. No proof of this, just a wild guess.
4. I am not wearing out a TC clutch I don't use .

I do get the case you all are making for leaving it locked in 4th / 3rd (or even 2nd). I am not completely sold on leaving it unlocked in 4th. I think I will take some logs this weekend and apply the slip reduction changes. Will check back in with more info later. Thanks all for the wisdom and help!

[mikez71]

No Problem! Glad it was / is helpful.

I wanted to check back into this thread after driving the Tahoe for about a month with the TCC / DFM changes to update on my observations. Note I still haven't made the slip changes yet, as I wanted to test each change in isolation.

Here are my observations so far on the "no TCC lock in 1-4":

Negatives:
1. It combined with the DFM / AFM delete does seem to eat into fuel economy reducing it by about 25% around town (only about 5% on the highway).
2. There is some "slack" in going on / off the throttle that I can notice, especially in 2-4. Though I will say that my wife told me she doesn't notice anything different about it ... so I might be noticing it because I expect to notice it.
3. It does generate some heat around town, though with the thermostat delete, it never gets above 150 even when it was 90 degrees out.
4. I don't have much engine breaking (if any) especially in first even if I have tow haul mode engaged. I admit I don't understand much about the TC mechanics when it comes to this and I haven't taken any logs yet (need to do that this weekend) to see what exactly it is doing here (is it actually dropping to 2nd, or is it really holding first?). I do enjoy having a bit of engine breaking, especially in heavy traffic, but it may be the price I have to pay for not locking the TCC.

Hi TheDoofus, glad to hear your reviews.!

Regarding converter slack, I was looking at your stock 2017 tune, and the upshift speeds are significantly raised in portions vs. the 2015 tune.
(There are slight ratio differences, 3.08 vs 3.06 and possibly tires?) Not sure what other changes are causing all the difference..
(looks like some TCC pressure and apply ramp changes, driver demand in engine torque management..)

BUT, I believe lowering(!) some of those shift speeds may help on the slack feeling and overall shift smoothness since you've disabled 1-4 TCC.
It maybe worth testing the 2015 schedule just to see how it feels as a comparison. It could help mileage as well...

When I tried the 2017 schedule in my 2012, it's shifting a tad high/late... but I do notice less potential bogging.
I'm trying to keep the numbers as high as possible, without any driveability tradeoffs..

2017 Tahoe vs. 2015 Tahoe
17shift.png15shift.png

Now I know there are other changes between years, so copying and pasting isn't going to give me the optimum tune.
But the 2015 schedule is such an improvement over 2012 in every way, so I'm extremely happy these other tunes are available!

Regarding engine braking, yes I think you lose that with the TCC unlocked. Although you can set your downshifts earlier maybe.
I miss the engine braking too, but figure I'll go into tow mode if needed.

[chevy_man]

I've never looked at one of these files nor tuned on one of theses specific transmissions but if you apply normal thought process to keeping a electronic trans alive, why has nobody mentioned much about torque management for the trans? In strictly terms of extending the life of the trans. would one of the best practices be to decrease as much torque input as possible during a shift? The compromise is comfort. Basic rule of thumb, the less slip you have in a clutch system the longer it will last. In order for a OEM to get comfort they need to let the clutching mechanisms slip and or absorb torque, that is the action that ultimately causes them to fail.

There seems to be a lot of mention about the TCC but as long as the TCC doesn't send shrapnel into the fluid it has little to do with the rest of the trans. as far as longevity. I would lean toward keeping it locked up as much as possible to help keep heat generation down and keep the eng. rpm lower for a daily driver. I know the lock up schedule is a compromise of many factors and locking it up as quick as possible in most scenarios is the best approach to extend TCC life. Obviously there is a lot more to it than a couple paragraphs can describe, but in general, shift it quicker, with more psi, and little torque applied as possible to help extend the life.

You mentioned you like some of the things it does in tow/haul mode, some of what I mentioned is likely what they are doing when you push that button. The OEM's are walking a tight rope with compromise of many variables, cost and satisfaction level from the customer likely being at the top of the list. How inexpensive can they make/buy it and still have the customer satisfied so they are repeat customers? They could build the trans to last twice as long as it does with a control strategy that would support that, but how much would it cost and when would you buy another one?

In my opinion if you approach the control strategy as if you were about to double the output of the engine how would you change the strategy for the trans. to support the additional input? Some of the answers are above.

You can keep torque management during the shift. Doesn't have any effect on lock-up.

My factory converter failed and the carbon got stuck in everything, putting it into limp mode and causing a glitter bomb from all the parts that got immediately unhappy. Turns out carbon stuck in all the passages isn't good for normal operation.

Some will claim that the factory stamped converters can fail at 0 slip because the cover isn't strong enough and flexes under the extra pressure. I went billet because it's a bitch to change the converter on jackstands in the driveway (although I did the full R&R this way).


I personally put a billet converter in and set the slip to 0 and have no complaints. I also still allow lockup in 2-6 just because I do a lot of cruising/towing down 20-45mph gravel roads to go hunting/fishing/camping and slip makes heat no matter what.

I have a 7200lb CCLB with a 6.0 and 6l90e. Stock trans made it 315k.

[[email protected]]

Am I the only one still using BlueCat software?

[mikez71]

Sounds like everyone recommends it. !
The ONE time I tried filling in the variables, my shift speeds were lower than I wanted.
I most likely did not enter all the data correctly.

Would like to add, I tried lockup in 3rd. Its boggy with full lockup on 3.08 gears in my 2012.
Too lazy (poor of a tuner) to try and dial in the tcc apply/release so it's smooth and not boggy.
I'm sticking with 1-3 unlocked, 4-6 cruising gears locked.

Also would like to add, the stock 2015 schedule in my 2012 (both 3.08 gears) tends to run a little high.
Ended up reducing (from 2015 schedule) shift speeds upto ~2mph in areas of 2-3 and 3-4 shift. Maybe if I had lockup in those lower gears that might account for the speed difference.