AFM Vibration - now with new heavier shudder

[14silverado4.3]

Hi all, I am familiar with AFM vibration however this is a new twist.

 

4.3 / 4WD / 3.42 gears

 

I have noticed over the last several months the following on Highway cruise mostly

 

1. 74 MPH downhill, cruise control on - on top of the regular low resonance vibes from AFM, I am getting a cycled vibration. It is heavier and comes on for 3-5 seconds, then off. Repeats 4 times on a 1/2 mile down hill grade.

 

Feels like small speed bumps

 

 

2. The other issue I have is when in AFM transitions from V4 to V6 during low throttle input, heavy vibration, it almost feels like torque converter issues.

 

 

Been to dealer, this is normal. I don't think it is but want some ideas from the all knowing GM-Trucks congregation...

I would like to go back to the dealer with a PIP if there is one.

 

Has anyone experienced this and what was the outcome?

 

[Fishbait]

My 2015 6.2 8 speed exhibited those very same issues. The dealer replaced the torque converter and that fixed the problem. So far I have put 3500 miles on the new torque converter and the truck runs and shifts smoothly.I would go to a different dealer if that is an option.

[14silverado4.3]

My 2015 6.2 8 speed exhibited those very same issues. The dealer replaced the torque converter and that fixed the problem. So far I have put 3500 miles on the new torque converter and the truck runs and shifts smoothly.I would go to a different dealer if that is an option.

Thanks, I will see what I can do.

[Donstar]

You describe very specific situations which I don't know for certain if this will happen in my truck. I can tell you that I have the same power combination as you and the only indication I have of a switch between V6 and V4 is the notification in the DIC. My guess is that if you can feel the switch under any conditions that it is not normal!

[FishinJ]

My 2015 6.2 8 speed exhibited those very same issues. The dealer replaced the torque converter and that fixed the problem. So far I have put 3500 miles on the new torque converter and the truck runs and shifts smoothly.I would go to a different dealer if that is an option.

 

Had the same exact thing and it's been smooth since the replacement.