2016 Sierra RPM Dip

[Wetbeard]

Hi guys. 1st post here, been reading a lot of great info on the forum.

 

I put down a refundable deposit on a 2016 AT 6 speed on Friday but I wouldn't sign the papers until a mechanic checked the thing out. It had the flutter between 2&3 while shifting. Also, while idling in park the rpms would dip from 500 to just below the 500 hash, the truck would shudder, then they would bounce back up. This happened every 30 seconds or so.

 

After I left the dealership I had a buddy check with his father in law who is a GM mechanic. He said GM is telling them that this issue along with the weird shifting are both related to the vehicle learning your driving habits. Haven't heard from the dealer yet this morning. Anyone else have this? I drove an 8 speed and a demo with 3k miles on it and neither one did it. Thanks!

[Brianibew]

The rpm bobble won't get better in time, the trans issue may or may not. I know, both those answers sucked. Do some searches on here, all kinds of reading on both those topics.

[Wetbeard]

Thanks for the reply. They just called and there was a bad spark plug connection. He said the check engine light came on while the service dept had it and they have it running smoothly now. i guess I'll see when I have time to go back on Wednesday. If it's still doing it I'll just wait. They have 5 more of this exact truck on order and 5 with the 8 speed coming as well.

[InertiaFaze]

Hi guys. 1st post here, been reading a lot of great info on the forum.

 

I put down a refundable deposit on a 2016 AT 6 speed on Friday but I wouldn't sign the papers until a mechanic checked the thing out. It had the flutter between 2&3 while shifting. Also, while idling in park the rpms would dip from 500 to just below the 500 hash, the truck would shudder, then they would bounce back up. This happened every 30 seconds or so.

 

After I left the dealership I had a buddy check with his father in law who is a GM mechanic. He said GM is telling them that this issue along with the weird shifting are both related to the vehicle learning your driving habits. Haven't heard from the dealer yet this morning. Anyone else have this? I drove an 8 speed and a demo with 3k miles on it and neither one did it. Thanks!

 

Often misunderstood, the vehicle doesn't learn your driving habits. WRT the trans, the TCM compares certain measured parameters against desired/expected values and then makes adjustments as necessary in order to make the measured and desired values as close as possible.

[TJay74]

 

Often misunderstood, the vehicle doesn't learn your driving habits. WRT the trans, the TCM compares certain measured parameters against desired/expected values and then makes adjustments as necessary in order to make the measured and desired values as close as possible.

 

 

You are actually incorrect on this part, there are several transmission adapt tables that "learn" and or constantly learn the driving style of the vehicle in order to improve shifting performance.

[tnchevy]

Then GM is not very good at making transmissions that "learn" these days!

[InertiaFaze]

 

 

You are actually incorrect on this part, there are several transmission adapt tables that "learn" and or constantly learn the driving style of the vehicle in order to improve shifting performance.

With all respect, I wasn't incorrect and neither were you. Rather I think we're saying quite the same thing. My point was that when the term driving style is used it infers that the TCM is going to learn differently from one driver to the next, that is that it's learning something about the way one drives the vehicle. Rather it monitors how a particular transmission performs compared to predetermined desired performance. It's quite as simple as that and there are many parameters that are adjusted. You are quite right that learning continues to occur periodically throughout the life of the vehicle, not just during the initial days and miles.

[f8l vnm]

I'm still having trouble processing this learning bs. Why can't it just shift right and smooth from day one ? Why does it need to learn anything ? Stupid time at gm

[TJay74]

Every transmission out there uses trans adapt tables. This isnt a 1st gen 4L60E that has minimal shift logic, there are hundreds of shift logic tables in the 6L80E and above transmissions.

 

People want to gripe about the shift logic, blame it on the market users of the vehicles. Consumers complained about how harsh the torque converter locked up, so now GM slips them in so you don't feel them look up. People complain about harsh shifts so now GM uses torque management and shift logic so you don't feel the shifts. The progression of shift logic comes from the feedback coming from the consumers.

[rilcoat]

Hi guys. 1st post here, been reading a lot of great info on the forum.

 

I put down a refundable deposit on a 2016 AT 6 speed on Friday but I wouldn't sign the papers until a mechanic checked the thing out. It had the flutter between 2&3 while shifting. Also, while idling in park the rpms would dip from 500 to just below the 500 hash, the truck would shudder, then they would bounce back up. This happened every 30 seconds or so.

 

After I left the dealership I had a buddy check with his father in law who is a GM mechanic. He said GM is telling them that this issue along with the weird shifting are both related to the vehicle learning your driving habits. Haven't heard from the dealer yet this morning. Anyone else have this? I drove an 8 speed and a demo with 3k miles on it and neither one did it. Thanks!

This is my recommendation. If the truck has the vibration don't buy it. Lots of us are having the issue and it only gets worse. I have had the shims put in and it helps a bit but I still have it. If you want to have a smooth idle and smooth shift, buy a dodge, Toyota, or even a ford. Other than that get a programmer. Mine idles at 500 and drops as low as 400 and the dealer says its all good. Not just 1 dealer but 3. Run like the wind, I should have