Dealer did nothing "normal" driving (then come jump in my beater '97!) So looks like a tune will have to cure it somewhat.

 

Like I said though..... the tuning on the 8 speeds isn't exactly fantastic... and I really doubt firming up your shifts and whatnot will do a lot for you. The support isn't really there.....

 

Don;t the 6.2 Camaros and Vettes use the 8 speed auto? What are those guys doing?

I figure a lot of it is TM pulling timing out before each of 8 shifts.

 

The same thing the truck guys do....live with the fact the 8 speed has diddly for support. If you think it shifts bad toggle the torque management settings to off..... it feels real great then.. mine shifts about 1000 times better with it on. You can't "reduce" torque management... you have a button, on or off. You don't have proper tuning with the 8 speed trans... doesn't matter what platform it is. I haven't looked what changed with this latest revision of HP they released about a month ago as it's so full of bugs and freezes I can't be bothered until they fix it. Not one poor shifting 8 speed has been rectified with any aftermarket tuning so good luck with that lol. GM needs to fix your transmission mechanically first.....

 

Same problem, my vette has been having the same problem since it had around 2500mi, still has the issue even though they did a computer update. From what i've read online, some people have had only the stator replaced, some the tq, and others the whole transmission. For some it has fixed the issues, while others continue to have issues. Theres a new TSB out for trucks I saw recently.

 

Got a TSB number since GM thinks it is "normal"? And why they aren't even going to mechanically fix it.
" Not one poor shifting 8 speed has been rectified with any aftermarket tuning so good luck with that lol. " Not what I wanted to hear!

It is moderately better in Tow/Haul.

 

I would suggest disabling grade braking but your issues shouldn't be affected whatsoever by it. I see new complaints with this transmission daily. Mine is getting the stator tsb done to fix the delay from park but that's all I have for a complaint really. I will see if they can make sure the flash in it is the latest but I imagine that's part of the tsb.

With your issue I wouldn't even be conviced it's the trans and could be an engine problem...

 

How soon until we see the 8sp replaced by the 10sp in the trucks? Maybe 2018 in the denali/high country /escalade?

 

Disabled the braking last might helped a little.

Drop into reverse from park to go out the driveway and a big lag then grabs.

TSB number?

 

Your problem sounds a lot like a buck/bobble torque shaping routine that is active from a stop and in between gears. With the additional available ratios and corresponding gear sets, not to mention the increased torque of modern engines...this is really the only way to put a transmission like this into production.

Unless you have comprehensive calibration access to the torque model via whatever calibration software you're using, you'll have to wait until GM releases an update for it. The more complaints there are, the more likely there will be an update...