5.3 A8 noticeable shudder when in AFM Mode

HondaHawkGT · May 27, 2019

Yeah I suppose that if I was at a steady 60 mph and slowly tried to accelerate to 65 mph, I would probably sense a small amount of rumble from being in cylinder deactivation. It's still a whole magnitude less noticeable than my 2014 was. I have to focus to notice it in the 2019 where in the 2014 it was in extremely noticeable.

175vTrailbossLT · May 28, 2019

dumb question but is there a way to know what the DFM is currently doing or how many cylinders are being ran at any point in time? Some of the comments here indicate so.

Wiggums · May 28, 2019

I don't see anything in the dashboard to indicate how many cylinders are running.

diyer2 · May 28, 2019

My 2012 tells you if its in V4 or V8 mode.

DIC screen shows it.

eppieguy · May 28, 2019

No way to tell, nothing on the DIC

econometrics · May 28, 2019

Yep, that's what is new and different between AFM and DFM... the DIC does not tell you. Nothing on the truck does.

Ironically, you didn't need it to tell you with AFM, because you could easily feel the vibration whenever it did!

HondaHawkGT · May 28, 2019

They don't display it in the DIC for whatever reason. The only way to know what pattern the engine was using is by using a device plugged into the OBD2 port. When GM first showed the trucks to auto journalists, they had a device that plugged into the port and would show what pattern the engine was using.

OnTheReel · May 29, 2019

The patterns are just too complicated. No chance the buying public would be able to understand when it’s displaying fractions or whatever.

I think maybe an “ECO” light might do the trick. At least it would tell you when the truck ISN’T running on all 8. Plus people seem to like anything “eco” these days...

After over 4,000 miles under my belt on this truck, there is one pattern I can always spot because the exhaust note (performance exhaust) has a strange rhythm to it. Usually light throttle around 30 mph. Other than that it’s impossible to tell.

Bikeman · May 29, 2019

Dfm is pretty seemless ln the 19's, no complaints from me, is just drive it

ndking1126 · May 31, 2019

about 450 miles on my odometer, and so far DFM has been seamless except for light throttle at 45-60 mph (give or take). Feels to me like when you're driving a standard and pick 5th gear when you should have gone into 4th and the engine is barely able to stay on.. the engine vibrates and kinda sounds rough in my truck. It's not really bad, but it is noticeable and annoying. To me it feels like this one particular DFM mode just needs to be removed because it is too aggressive with trying to save gas. Pick one that provides a little more power.

Gas mileage on the first tank was 19.7 with a good mix or interstate and around town. I was impressed.

Wiggums · May 31, 2019

11 minutes ago, ndking1126 said:

Feels to me like when you're driving a standard and pick 5th gear when you should have gone into 4th and the engine is barely able to stay on.. the engine vibrates and kinda sounds rough in my truck.

Couldn't have described it better.. this.. is.. spot.. on...

ndking1126 · May 31, 2019

15 minutes ago, Wiggums said:

Couldn't have described it better.. this.. is.. spot.. on...

I think what annoys me most is that it never did it during the 57 miles of test driving my wife and I did.

Edited May 31, 2019 by ndking1126

Wiggums · May 31, 2019

21 minutes ago, ndking1126 said:

I think what annoys me most is that it never did it during the 57 miles of test driving my wife and I did.

I didn't feel it when I test drove it. First time I felt it, I wasn't looking for it. Thought it was odd and could be transmission-related since I've driven cars with torque converters back in the 1980's when you could feel it. I rented cars practically every week and I drove at least 25 or 30 cars every year so I knew some cars had good torque converters, some don't. Now, I know how to get DFM to happen, it's not that bad. You really shouldn't be feeling it if you're not looking for it. I think I'm more sensitive to vibration than others and feel things when others don't. I'm always the first to feel an earthquake.

Edited May 31, 2019 by Wiggums

NW-99SS · June 14, 2019

UPDATE:

Truck was surging with the cruise set at 70mph last night. Flat highway, RPMs were moving around 100 give or take while it seemed to be unable to find what DFM mode it wanted to stay in.

I'm glad that my work owns this truck, pretty sure it's going to see warranty work for the trans/DFM very soon.

HondaHawkGT · June 14, 2019

8 hours ago, NW-99SS said:

UPDATE:

Truck was surging with the cruise set at 70mph last night. Flat highway, RPMs were moving around 100 give or take while it seemed to be unable to find what DFM mode it wanted to stay in.

I'm glad that my work owns this truck, pretty sure it's going to see warranty work for the trans/DFM very soon.

I would have the dealer check it over if it's as bad as you're saying it is.