Dynamic Fuel Management (DFM) versus AFM

[gmcsierra71]

Good article on the differences between Dynamic Fuel Management (DFM) versus Active Fuel Management (AFM):

 

https://www.chevyhardcore.com/tech-stories/engine/gm-escalates-cylinder-deactivation-with-dynamic-fuel-management/

 

Highlights:
- Spring-loaded lifters in all 16 positions so that all eight cylinders (instead of only four) can now be selectively deactivated.
- DFM eliminates the Lifter Oil Manifold Assembly (LOMA) used by AFM and replaces it with dedicated oil control valves in the lifter valley.
- AFM has Four Oil control valves that utilize oil pressure to deactivate lifters. DFM has Eight Oil control valves,
- GM tells us there are 69,904 lines of code required to control the DFM’s various cylinder firing sequence.

 

 

 

[econometrics]

Thanks for posting this. Very in-depth. One of the best I've read. 

 

DFM is quite an amazing technology, IMO. It's clear that most of us with the 5.3L DFM are getting really good MPG with it. I think it's out-powerforming the stated EPA #s. 

 

Also, I've had mine for 3200 miles now, and I cannot say that I have felt DFM more than 2-3 times. My 2007 with AFM was extremely noticeable, with the dreaded V4 vibration/noise super easy to hear and feel. 

[wizard4878]

Mine has 6200 miles and I haven't ever been able to tell how many cylinders it's running on,  super smooth transitions.

[MacLaren]

23 hours ago, wizard4878 said:

Mine has 6200 miles and I haven't ever been able to tell how many cylinders it's running on,  super smooth transitions.

I'm with you. Although I'm just a bit over 700 miles, I could swear mine is just a regular V8 engine.

 

[diyer2]

Well my AFM has been flawless.

[Billet Bowtie]

That's why they make these trucks so quiet. If you put a moderately loud exhaust on them you can hear (and therefore feel) every time it deactivates cylinders. When I put my exhaust on I was amazed how much of the time the truck runs on less than 8 cylinders. It deactivates cylinders a lot.

[Fuelie]

Is there any way to tell how many cylinders it is running on? On my 17 and 18 it was on one of the menu's.

I don't see it on my 19.

Tom

[eppieguy]

Nope 

[MacLaren]

On 7/23/2019 at 2:41 PM, diyer2 said:

Well my AFM has been flawless.

I absolutely believe that.

These Silverado trucks are just good. Period.

Most people around my neck of the woods love them. No matter the year honestly. 

Not to say there are more Chevy owner than Ford owners. I have no idea. But, the Chevy owners all really like their trucks. 

[Rob41]

Love the mileage with the 5.3 and it's actually got a higher factory towing rating than the 6.2 does.  I've never felt the DFM but the auto shut off is driving me nuts.  I'm hoping I'll eventually train myself to remember to push the off button every time I start the truck.  Otherwise I'll have to pony up the $75 for the disabling connector.