Dynamic Fuel Management woes.

[MTY55]

I'm driving a 23 Denali  with a 5.3 10spd. When I'm driving in town in the 25 to 40 mph range, and between 1000 to1500 rpm. I get an annoying low grade vibration and drone sound when it drops out of V8 mode. Sometimes when it drops cylinders and transmission at the same times I get a pretty hard shift and shudder. I was at the dealer the other day and they told me this is pretty much a common occurrence for these newer models. Previously I had a 20 SLT 5.3 10 spd with DFM and that one went through the transition seamlessly I never even knew it was happening. I was talking to a guy the other day he has a 5.3 in an Elevation and he is experiencing the same condition. Just inquiring if this is a widespread flaw in the system. 

[cef2lion]

I have a 22 ZR2 with the 6.2 10 speed. 10K Miles. Acts similar. A shudder and what feels like the transmission down shifting. Mentioned it to the dealer twice and got the same answer you did. I assumed it was DFM. I have tried tow and L9 mode to defeat DFM and rule out DFM. Not sure it makes much of a difference. No CE light to date.

[KARNUT]

It’s probably the nature of the beast. Even on my Odyssey sometimes there’s a slight shutter at slow speeds when it modulates from cylinder deactivation and gears. You don’t feel anything at cruising speeds with just the cylinder deactivation. But if the transmission is in play sometimes a little shutter. 

[MTY55]

4 hours ago, cef2lion said:

I have a 22 ZR2 with the 6.2 10 speed. 10K Miles. Acts similar. A shudder and what feels like the transmission down shifting. Mentioned it to the dealer twice and got the same answer you did. I assumed it was DFM. I have tried tow and L9 mode to defeat DFM and rule out DFM. Not sure it makes much of a difference. No CE light to date.

If if run in L9 everything seems normal no cylinder deactivation and all is smooth. 

[MTY55]

4 hours ago, KARNUT said:

It’s probably the nature of the beast. Even on my Odyssey sometimes there’s a slight shutter at slow speeds when it modulates from cylinder deactivation and gears. You don’t feel anything at cruising speeds with just the cylinder deactivation. But if the transmission is in play sometimes a little shutter. 

Mostly only at low speed but Saturday I was on the highway with cruise set to 60 I believe the it was around 1200 RPM I definitely could feel it was only running on 4 cylinders. Just touched the gas pedal and it went back to 8 cylinders.