Plan on taking the truck to the dealer and seeing what of the 3-4 pages of driveability TSB updates might help these issues and then getting a tune to improve it afterwards. When my wife notices a throttle lag and surging you know it is obvious!
Here's the list I'm going to give them any other thoughts you guys have or specific updates for this stuff before a tune?

1) Dangerous Throttle Lag- There is a 1-2 second lag between stepping on the gas pedal and the truck going. This is dangerous pulling out into traffic or across traffic, changing lanes. You have to have pushed the pedal in so much when it finally goes it is like you floored it.
2) Part throttle light acceleration like from a stop sign it surges-accelerates then falls on it’s face like no power then accelerates again. It feels like a truck with a carburetor that is not jetted correctly or is running out of gas. Or it could be searching for which transmission gear it wants to be in and dropping power before the shift even though it is light throttle not full throttle shifts.
3) Part throttle stop and go like on Katy Freeway traffic surging then clunks transmission after letting off gas then back into gas. Maybe computer is thinking of downshifting then upshifting.

 

I think the clunk is pretty commen and I believe somebody had their transmission replaced because of it over on the gmtrucks forum. I need to take mine in, not holding my breath for them to do anything about it tho, good luck.

 

Some are a lot worse than others. My 2015 only has a delay from park to engage into reverse or drive with there is a TSB for and the local dealer has ordered the parts they need to fix mine. Once that is done I should be good...... just need to get my 8 speed to follow the commanded shift RPM in HP lol. I haven't downloaded the latest update of HP to see what they added but the current rev I have really won't help you with that clunking stuff. It's pretty limited.

 

Clunk is not bad enough to really worry about but mechanic buddy says that gets them to look harder at TSBs. He is the one that based on my VIN there were 3 pages of driveability issue and one of tranny driveability issues. makes you wonder how the computer programmers have that many patches out! His impression when he had a Tech 2 was once you load them there is no going back so usually you want just the specific ones loaded related to the issue.

I will say WOT it hauls but and has the best brakes feel and stopping of anything I have ever driven. Responsive steering no wandering just a little light on the feel like Grandma's Caddy.

The lag off idle if below 1/3 throttle is pretty significant and the surging when at part throttle. Like I said my non auto wife notices it!

 

What build date is your truck on the door sticker? Mine is February of 2015 and if it was January or December of 2014 according to the dealer I took it too they would have replaced my transmission completely for the delay from park problem. Newer just gets the stator replaced and whatever else as I haven't seen the full TSB. When I drop it off I am going to ask they install the latest and greatest settings in the TCM and see what it does.... if they will. I really have no drivability issues beyond the odd clunk that doesn't bother me.

 

Sounds like you tuned it yourself? Do you mind sharing your tune? I just got hp tuners, but I'm new to all that. Ive read the stock tune with v3.2, i was wondering if I could improve driveability with a few tweaks to the trans.

 

It's not a tune I built totally no. I got a guy to dyno tune the truck and dial in my timing and air fuel. I have added or changed things after but for now the trans is the biggest thing I need to work on. He raised line pressure and just set all the torque management settings to "off" as you have no control beyond on and off. That didn't work so I re-enabled the tm and have been playing with shift points. If I can actually control the torque management properly then I will start reducing it.

 

Dropped off at dealer yesterday "all normal when tech drove it". Try again have shop foreman drive it.

Might just have to get a tune.

 

Try this:
Press & hold the tow/haul button on the shifter for 5 seconds. When you release it you should see a message in your DIC saying "Grade Braking: Off" if you did it right. If you let go of the button too soon it'll just put you in tow/haul mode.

Many people, including myself,have done this and report that it makes a noticeable improvement with the way the transmission behaves. The only downside is that you have to do this each time you turn the car on, there is no permanently disabling it (not sure if you can make it default to off with a tune though.) Even though I do this I still get a delay and a terrible jolt in the driveshaft when shifting from P or R to D. I was told that my trans is up to date and this must be normal....which is absolutely bullshit as it's pretty much common sense that isn't normal or good for the trans.

Now it doesn't completely make things awesome in all areas, but for me it made a big improvement and the truck doesn't seem confused as to what it should be doing with the trans.

 

The surging is much less in Tow Haul so I'm sure it is computer related.

I'll give it a try when it comes back.

Yep pop it into reverse and hit the gas nothing happens then bang going fast.