I have a 2012 Impala with a 3.6L LFX engine and a 6T70 trans. I'm looking for some help understanding the TCC lockup settings....

The stock tune has a "6" in the 4th gear apply field (for all pedal positions - and has a "1" in all 4th gear TCC release fields *except* for the zero-pedal field, which has a "30" (4th->3rd downshift occurrs at 25mph). So basically, the TCC is locked at all times in 4th gear. But - what is up with the 30 in the zero-pedal TCC release field? Since 4th gear zero-pedal apply is set to "6" and 4th gear zero-pedal release is set to "30", what actually happens? I've always read that the apply value should *always* be higher than the release value. So what really happens when coasting in 4th gear? Is the TCC always unlocked in 4th gear while coasting with those values or does it actually release when you are coasting in 4th gear and go below 30mph?

I haven't used the stock values in a long time, so I'm not sure how it reacts (no logs to look at). In my tune, I've been setting the TCC to apply a few MPH after upshifting into 4th gear and then releasing a few MPH before downshifting out of 4th gear. However, I've noticed a few instances where the RPM's jump around when letting off of the gas in 4th gear (I suspect it's becuase the TCC is locked at first, then unlocks and then downshifts into 3rd - all rather quickly when slowing down), so I think I want to go back to keeping the TCC locked at all times in 4th gear, but not quite sure what to do with the zero-pedal fields. Should I leave them at stock values or should I make the TCC unlock a "1" like the other pedal positions?

Thank you!

Also - what decides whether the TCC is locked while coasting - is it strictly controlled by the zero-pedal apply/release fields or do other things affect it? From what I've seen, it doesn't seem consistent with the apply/release fields at all times...

Thank you!