Get it declared a lemon and make them give you a new truck. That just sounds like crap to me.

 

The government forced CAFE is your problem.
I have the same 6 speed and usually "around town" legal speed is 30 mph. My truck wants to be in 6th gear and V4 mode most of the time.
5th gear is overdrive, 6 th gear is the 2nd overdrive.
30 mph in overdrive!!!!!!! You wouldn't drive a manual that way.
On top of that, GM programmed the computer to back off on power when you mash the small pedal at a traffic light.
You can get a "tune"; but, people say it voids the GM warranty.
I use the M selection and keep the transmission in 4th, or sometimes into 5th. I find that works quite well.

 

LOL @ pulling power and torque of a new half ton

 

When I first went from factory 17" wheels (don't remember tire size) to 20 wheels and tires roughly 1.5" taller I had this problem, I didn't have a tuner on the truck at that time either, the doggy issue bothered me.
I tried as Ray suggested using the manual mode, but being lazy I would forget about up and down shifting and run the rooms higher or lower than I wanted. Someone recommended activating the tow/haul mode so I tried that, it worked well, and after a few thousand miles I noticed my trans was shifting better without tow/haul activated, things got even better when I deactivated the AFM. Now days it drives more like I think it should.

 

Thanks tbplus10. I kept the Z71 wheels but went with 275/70/18 BFG at tko2's which measure as 33"+ tire size and that might be affecting it a little. I did try the tow haul mode for a little while but didn't really like the way it shifted then. I will try the manual shifter and see how that works. Still sux that we have to "make" it work for the that we have to pay for this latest greatest trucks. I am going to have the dealer service transmission expert drive it to see if it is the truck or just me being picky. Will let you know what they say.

 

I had the same issue with my 2011. I tried the M5 and tow haul and got tired of it.
I ended up getting the Range module and everything is fine now. V8 forever.

 

Well, to the OP; if you went to larger tires, I can see why you would notice the "lugging". Larger tires effectively changes the rear axle ratio, putting you into a lower rpm range for any given mph.

 

If you put stock tires back on it does it have this problem? You're basically complaining that it's not driving the way it was designed because you changed the design.

 

If you went to larger tires, the truck needs to be reprogrammed for the larger tire so the electronic controlled trans can adjust the proper shift marks. MPH, RPM and vacuum, temperature all affect shift patterns and maybe throttle sensor thrown in the mix. I'm not too sure about the statement that the transmissions learns how you drive?

 

WorthFlorida, I was thinking about the tired but will the dealership handle the program or will I have to buy one? As for the tranny, the service manager said it is called "ATP" or adaptive transmission program. It adapts to your driving patterns.

 

The PCM has the ability to monitor your driving habits. It has the ability to self-adjust for the way you drive the vehicle. The "adjustments" are overlaid on the factory parameters and will continue to adjust as you drive. Little things like shift points (up and down).
These "learned" parms are removed if battery is removed from the PCM.

 

Thanks Ray. Then perhaps James axe is driving with a light foot and with larger tires the PCM is reading low RPM's verses MPH, therefore, the driving is at the light end of curve. If James were to drive a little harder on the gas for higher shifts and get the PCM programmed for his tires, the problem may fix itself.

 

Yep, that couuld very well work..........to a point

 

When I went to a larger tire/wheel package I had a dealership do the reprogramming on my PCM, about a month later I bought a new programmer that had the ability to make the changes.
I've since started using a Range technology AFM delete with the reprogrammed PCM.
Keep in mind as someone earlier stated larger tires require a gear swap, with at tire wheel change of only a few inches you can sometimes get away with just the PCM update.

 

Guy's thanks for the input. I ended up finding a local car guy that has a custom tuning program and we hooked up the truck and after almost 3 hours of driving and tweaking all 6 gear shift points, the truck if finally the way it should be. Now she has solid shift points, she's holding gears and rpm's until it should shift and also turning off the AFM, she's perfect. Best $300 I've ever spent!! If you are interested in getting a custom tune and are in the north west Arkansas area, look up tuned by JP!!

 

Good deal. Custom tunes are always highly recommended

 

I realize this is an old post, but my 2015 Sierra shifts like crap. If you start off like you should, it lurches between 1st and 2nd. I've had the local GM store reprogram the tranny, but it still shifts funky. I'm going to try the custom tune thing.

 

As RayVoy wrote when the battery is disconnected the learn parameters are lost therefore the trans goes back to factory default. The GM dealer may have cleared them when you had them work on it. I would disconnect and reconnect the battery. Wait a few minutes before reconnecting. If the problem is exactly the same it may be s mechanical problem.

 

Tow haul mode...
I know this is old but I received a class action letter in the mail about this and I have to contact them. I have a 15’ Sierra SLT and have this issue. The service writer said “it could be the way drive it” yea thanks bud. Anyways the easier method is leave it in tow-haul mode. Then you don’t have to reach over and push a button when you need power.

 

A class action letter on what, Tow/Haul?

 

No on the initial issue which is the shifting lag/ delay the GM programmed into this. The Tow/haul mode is a programmed mode that raises shift points to let your truck act like a truck.

 

Lawyers and people amaze me...... Class action suits on how a transmission shifts and because dash plastic cracks; but no one cares about $7,000 engines falling apart because of AFM

 

I just rode in my friends 5.3l 16 silverado. Adult owned low miles never towed anything. Transmission was shuddering big time taking off. I had just asked him how it was holding up. He said it was holding up fine.

 

Hello Crew, anything else on the 6 speed trany? I have a 2016 Silverado 5.3L with 76600 miles. I took it to my mechanic and checked the computer and found nothing. He took it for a test drive and right away the Trany started Shuddering. I was not aware of that term. He changed the Trany filter and fluid. It's better, but I still some vibrations and strange sounds. He also reset the computer and I'm on my 4th drive. Nothing is improving. He told me I should take 8 drives, so the computer can adjust to my driving. Any ideas?

 

What year and how many miles?

 

2016 don’t know exactly how many miles. But it’s not very many. He’s gone 6 months a year offshore. I’ll find out. It might still be in warranty.

 

You don't hear of many problems with the 6 speed, the newer 8 speed has had some shifting problems.

 

I friend has the same shudder in a 6 speed, he fixed it by using the same fluid that the 8 speed requires.
The 8 speed has had a shutter problem from day one, they have tried a number of different fluids. The current recommended fluid is made under a Mobile 1 label.

 

Thank you, Ray!