tuning engine only (ecm) and not unlocking transmission (tcm) 2017 is this ok?

[Custom 68]

Like the title says I have read tons of posts and believe I understand I can unlock and tune only the engine portion and since the tcm is separate I don't need to send it off to be unlocked? I just didn't see a definitive answer but several that lead me to believe this is ok.

This is a 2017 Sierra 6.2 8 speed, What I have read just getting the ecm tune cleaned up some will improve the transmission shifts anyway. Will I still see gains in drivability only tuning the engine and skipping the trans tuning?
Thanks
Dave

[Ben Charles]

On stock to bolt ons I tell customer to save their money... I can make the trans shift better anyways through engine side..

On a boost setup or cam.. take advantage of RPM

[Custom 68]

Thanks Ben, a lot of what I have bookmarked has your name all over it... Ha. At one point I got to questioning with all I have read. I just wanted to confirm before I dropped the money to unlock this. I had understood the engine tuning will help with some of the "harsh" shifts under low power.
This is just my daily so I don't have any plans for cam or boost. My gen 3 in my 68 C10 has both... but that is a different critter.
Again thanks and I am sure I will be posting questions as I dip into this.
Dave

[gagliano7]

I have the same setup. I just tuned the engine side with some timing, E85 compatible, and turned off A FM. My trans shifts perfect with afm off.

[Custom 68]

Perfect then I will jump in so to speak. Ok a slow touch my toe in jump but you know. I have not had this truck long and the only issue seems to be when idling around in a parking lot it will "clunk" into second. It seems to shift and know what to do other than that. I am happy with the drivability but thought I could improve. I can't seem to leave well enough alone...
Dave

[kevin87turbot]

Perfect then I will jump in so to speak. Ok a slow touch my toe in jump but you know. I have not had this truck long and the only issue seems to be when idling around in a parking lot it will "clunk" into second. It seems to shift and know what to do other than that. I am happy with the drivability but thought I could improve. I can't seem to leave well enough alone...
Dave

This is a common complaint on the 8L90 transmissions. GM released an updated tune that helps the harsh 1-2 shift. It increased the shift time at low revs by 0.1 seconds max. It also slightly reduced the commanded shift pressures at low throttle.

If it annoys you, you might be able to get the dealer to flash it with the latest update. Or you can unlock the TCM and do it yourself. If you do unlock it, you might consider zeroing the TCC slippage tables as well. That's the other major problem with the 8L90's. They wear the converter clutch and eventually it will begin to shudder.

[Custom 68]

Thanks Kevin, I have had GM do the flush to the new fluid and at that time they updated the TCM.
I really can't complain i like the transmission. The only think I really find odd is that 1-2 shift but only at idle, I notice it when I drop my daughter off at school and idling thru the parking lot. It just clunks into second.
My truck (and trans) seem to run great I just thought I could clean it up some, the pedal feel off idle is slow or soft but other wise it all is good. I am just researching what can or should be done overall. I still may just leave well enough alone. lol
Dave

[MakesBadDecisions]

If you have the funds get an unlocked TCM. I have the same-ish truck and found that there is lot to be desired with the factory programming. Like kevin said, the zeroing of the convertor tables was huge. After working through the 1-2, 5-4 shifts, drivetrain ringing and in my opinion terrible shift scheduling it was a completely different truck.

[Custom 68]

Thanks for that, I will certainly keep that in mind. Like I had said it seems mine is all working together nicely. I have heard some are bad and then stories like you post that the tune makes them great. It would be nice to ride in each to see, I am sure to some folks me included we may not be as sensitive to it. I came from a 2004 Tahoe I had since new so anything newer doesn't have some of those old quirks.
Dave

[gagliano7]

Do you have AFM turned off yet? The only time my trans acted like was when AFM was on. With it off no more trans problems.

[Custom 68]

Do you have AFM turned off yet? The only time my trans acted like was when AFM was on. With it off no more trans problems.

No, I have not written any tune to my truck yet. I was still researching but that one seems easy enough to give it a try. I did put it in "manual" and gear 7 this keeps it from going into AFM and it didn't make any difference at least in the 1-2 shift at idle. by physically turning it off in the tune may behave differently.
I may be in the minority but I had hoped to leave this functioning in hops to gain some in MPG however as I read those gains maybe minimal anyway.
I will give it a shot.
Dave