Hi guys,
Found this forum scouring the internet for some answers. I have a 2016 Yukon XL Denali with the 6.2L and 8spd 8L90 -- since the day I purchased it as a CPO vehicle, the trans hasn't been right. Between sloppy shifts and a harsh 3 to 1 downshift, I have tried everything I could possibly think of to fix this. The dealer gave me the runaround for 12 months about how it's normal behavior, did the usual fast fixes, replaced the fluid, yada yada yada...that lasted only a few days each time... and then the warranty was over with and that couldn't care less.
Since then, here is what I've done:
• Diablosport tune (custom emailed) - no change and kind of made it worse
• Had a shop rebuild the trans completely and replaced the torque converter with a "heavy-duty" and billet front cover (they recommended) and changed the valve body plus a shift kit - correct fluid was used as well - this helped the shifts tighten up, but my 3 to 1 was still harsh when coming to a stop and gradually got worse over the following weeks after the rebuild -- the noise noticeably increased when...what I believe is the TC unlocking and locking during light throttle to deceleration or vice versa.
• Got onto the HP Tuner forums and purchased a tuner and decided to go at it myself. Read a ton and anything I did made little to no change in the trans. The only thing that ever softened up the 3 to 1 was pulling pressure on that specific shift. BUT it never totally went away. Chatter noted above has been the main issue now.
•• Tuning notes: (I took most things from the diablotune that was uploaded on my vehicle and downloaded it to VCM Editor as a baseline) TCC lockup is turned off in gears 1 through 6 + DOD is all disabled
• The last few weeks something has felt different and almost seemingly getting worse. On closed throttle decel, I can hear a audible clank from the TC (I believe) and it sounds/feels like something is holding it back, then a few seconds later it releases and I hear the TC clank again. Once I hit the light throttle again, another clank. This all happens over about 5-7 seconds, but this is newer and there were no changes to the tune during this time.
Since the rebuild, the noises have gotten louder. Don't get me wrong, this happened with the stock TC pre-rebuild, but this is worse than the stock ever was. It's very annoying as a daily driver, and I would go as far as saying that I hate it. It's made me hate driving the thing, as all I can focus on while driving is the noises it makes and how the truck bucks when coming to a stop sign. Tonight was the last straw for me. It's hard to admit this, but I literally cried today over this incredible feeling of defeat I've had with this truck. I'm a very handy guy, and I pride myself in doing most everything on my own, but the stress it causes me while driving has been unbearable lately because I don't know what to do next.
I came here in hopes someone can just straight out tell me the torque converter they put in is a POS and you need to get this one. Or at least give me an idea of what I can look at in the tune/hp tuners software or logs I can take. Even after setting everything back to stock, running a trans reset/preset, and even going as far as running a trans fast learn, the chatter has had zero change. I'm so burnt out with this thing that I started looking at newer styles just to get into a 10spd.
I appreciate you guys! Thanks in advance for any help that can be offered.
Found this forum scouring the internet for some answers. I have a 2016 Yukon XL Denali with the 6.2L and 8spd 8L90 -- since the day I purchased it as a CPO vehicle, the trans hasn't been right. Between sloppy shifts and a harsh 3 to 1 downshift, I have tried everything I could possibly think of to fix this. The dealer gave me the runaround for 12 months about how it's normal behavior, did the usual fast fixes, replaced the fluid, yada yada yada...that lasted only a few days each time... and then the warranty was over with and that couldn't care less.
Since then, here is what I've done:
• Diablosport tune (custom emailed) - no change and kind of made it worse
• Had a shop rebuild the trans completely and replaced the torque converter with a "heavy-duty" and billet front cover (they recommended) and changed the valve body plus a shift kit - correct fluid was used as well - this helped the shifts tighten up, but my 3 to 1 was still harsh when coming to a stop and gradually got worse over the following weeks after the rebuild -- the noise noticeably increased when...what I believe is the TC unlocking and locking during light throttle to deceleration or vice versa.
• Got onto the HP Tuner forums and purchased a tuner and decided to go at it myself. Read a ton and anything I did made little to no change in the trans. The only thing that ever softened up the 3 to 1 was pulling pressure on that specific shift. BUT it never totally went away. Chatter noted above has been the main issue now.
•• Tuning notes: (I took most things from the diablotune that was uploaded on my vehicle and downloaded it to VCM Editor as a baseline) TCC lockup is turned off in gears 1 through 6 + DOD is all disabled
• The last few weeks something has felt different and almost seemingly getting worse. On closed throttle decel, I can hear a audible clank from the TC (I believe) and it sounds/feels like something is holding it back, then a few seconds later it releases and I hear the TC clank again. Once I hit the light throttle again, another clank. This all happens over about 5-7 seconds, but this is newer and there were no changes to the tune during this time.
Since the rebuild, the noises have gotten louder. Don't get me wrong, this happened with the stock TC pre-rebuild, but this is worse than the stock ever was. It's very annoying as a daily driver, and I would go as far as saying that I hate it. It's made me hate driving the thing, as all I can focus on while driving is the noises it makes and how the truck bucks when coming to a stop sign. Tonight was the last straw for me. It's hard to admit this, but I literally cried today over this incredible feeling of defeat I've had with this truck. I'm a very handy guy, and I pride myself in doing most everything on my own, but the stress it causes me while driving has been unbearable lately because I don't know what to do next.
I came here in hopes someone can just straight out tell me the torque converter they put in is a POS and you need to get this one. Or at least give me an idea of what I can look at in the tune/hp tuners software or logs I can take. Even after setting everything back to stock, running a trans reset/preset, and even going as far as running a trans fast learn, the chatter has had zero change. I'm so burnt out with this thing that I started looking at newer styles just to get into a 10spd.
I appreciate you guys! Thanks in advance for any help that can be offered.
