Its my 2011 6l80 AWD denali transmission. I had it tuned and the tuner seemed to make it a little better but I am trying to confirm what exactly is happening on the 3-2 down shifts as it seems to bang a little when going into gear. This only happens after the transmission seems to hit around 100 degrees. It is the worst between 100 degrees and 135 degrees and then seems to smooth out a little more once temps are hotter. If I come to a stop on the quicker side, it does not seem to do it. 2-1 downshift is typically ok and all upshifts are good. I tried to hook up the Tech2 to perform the fast adapts and it just goes to a monitor screen and nothing happens. Also, while driving I was trying to watch the TCC slip but not sure what else I should monitor or how exactly to use the Tech2 to try and capture some info to post up here.
I would think it was tune only but it was doing this a little worse before the tune so I am trying to determine if any additional tuning could be done or is it not worth the effort to contact my busy tuner and it needs a valve body, etc.
Thank you!
You likely have wear in one or more of your compensator feed circuit components, which since it seems to be isolated to the 3-2 downshift, would be limited to that circuit...That said, there's still more than enough potential causes...
The specific data points you'd want to monitor are
TCC Slip Speed,
TCC Duty Cycle and
TCC command (on/off) as well as
shift speed and
gear selection (ie what gear you are in per the system vs reality) for all gear transitions (up and down shifts)...A fast adapt may help but I'm guessing, it will only be temporary as whatever's worn (can be multiple things) will overcome the TEHCM's adaptation efforts and your symptoms will return.
I'm going to be doing a video on the compensator feed system in those transmissions and publish to my Youtube channel in early May. There's almost no information about this particular system, how it works and the role it plays in the function of the transmission, which is somewhat surprising since it's so critical and important to the overall health of the unit.
Anyways, fixes include everything from servicing the TEHCM (sometimes clogged pressure switch diaphragms or worn seals cause clunky shifts) to rebuilding the entire transmission - all depends on what's worn and the extent of the wear/damage.