5.3 Dynamic fuel management

[Kdn85]

Hey guys hope all is well, I’ve read and seen in my own walks of life that the old active fuel management equipped 5.3s had issues and curious to those who have 2019 5.3s and up with the new dynamic fuel management how’s it going with it? I have a 19 Silverado with dfm and so far so good at 15k miles. From what I’ve researched I know this is a very complex technology and had me a tad bit concerned for longevity of the engine but I didn’t know about this system  when I bought it  I’m hoping they did a good job and won’t have the issues the old AFM systems had. And again I’m loving the truck so far , very nice! Thanks. 

[BlancoSilverado]

I haven't had issue and only seen one person on the forum complain about the DFM having a problem but that topic has been removed (that guy and myself were getting a little heated, LOL).

If there was some problems we would have seen them by now. 

[14SLE]

I previously had a 2014 crew cab Z71 with AFM and the 6-speed transmission. The combination of the "learning" transmission and the AFM system resulted in some horrible driveline clunks and jerks that never got better as the truck aged. I loved the looks of the 2014-18 models, but I was pretty much done with AFM-equipped engines and started looking at other trucks last fall. I liked the way the Titan drove (very nice and totally clunk free), but their resale value is awful. Tundras are nice, but ancient and get horrific fuel economy (yes, I know it is a truck and I can afford the gas, but I don't want a super-guzzler). Plus, Toyota's option packages are totally bizarre--the TRD sport package cannot be ordered on an upscale truck unless you get the TRD Pro, which does not even have automatic climate control. I test drove a '19 Denali at the end of the model year with an 8-speed, and the transmission slammed horribly before I even got out of the dealership lot. I passed on it despite a really good price. I test drove several 2020 models with the DFM system and 10-speed transmission and noticed no objectionable driveline behavior on any of them, so I traded my '14 on a '20 SLT/X31 when good deals were being made in January (pre-COVID). I have put about 13,000 miles on it so far, including a 1,100 mile interstate trip, and the truck still runs great. The DFM is aggressive and you can feel a "chuggle" at low speeds (20-30 mph), but nothing like the AFM system had. Unless the truck "learns" some bad behavior going forward, I'm pretty impressed with the DFM and 10-speed combination. I have averaged slightly over 20 mpg (per the DIC) for over 12,000 miles, including winter driving with remote start warm-ups. I drive about 40 miles round trip to work over back roads and drive a "fun" car during the summer. Manual spot checks of fuel economy suggest the DIC is reasonably accurate.

 

The DFM system is rather complex, so we'll see how it holds up over time. I bought an extended warranty, so GM will be fixing it if it breaks. Overall, I have been quite happy with the truck so far. I have actually grown quite fond of the Multi-Pro tailgate and the seats don't make my back suffer on longer trips. I just wish they would stop making the trucks bigger each iteration--parking the new truck is like docking a yacht. My wife won't even consider driving it.

[FL Chevy Guy]

I wish my wife didn't want to try driving my truck. She keeps asking to try driving it, and I pretend I don't hear her. 

 

Anyway, I'm surprised at how seamless the DFM runs. I really don't notice it, other than a change in the exhaust tone of I listen carefully. Out of curiosity, are there any mods or apps out there that tells you what cylinder configuration is running at any given time?

[14SLE]

I have not yet seen any consumer devices that tell what DFM mode is currently active.  There is a YouTube video showing a GM engineer riding along with the reviewer--the engineer is holding a device that displays a fraction indicating the current DFM mode.  DFM is much more complicated than simply shutting down individual cylinder(s)--it has 17 firing patterns it can cycle through (16 reduced cylinder patterns plus full V8 mode). There is a unique firing pattern for each mode where a cylinder fires a fraction of the number of times that it would normally fire for the specific number of engine rotations in V8 mode. There is a pretty good explanation of the system at this link, along with a graphical display of the fractional patterns.  https://www.enginelabs.com/engine-tech/gm-escalates-cylinder-deactivation-with-dynamic-fuel-management/.  GM claims it really doesn't make sense to say that you are only running on 'X' cylinders when that is not entirely accurate.  The good news is, unlike AFM, the cycling of cylinders on and off should reduce concerns about uneven wear between the cylinders that are always on and those that shut down.  Another reported AFM problem was higher oil consumption--I have not yet read anything that would suggest that DFM will be any better in this regard.  I guess time will tell. I'm guessing GM prefers to NOT display the current DFM mode, because that would make it easier for the driver to blame a specific problem on DFM being active.  Ignorance can be bliss (for GM). 

[redwngr]

DFM can change every cycle of the engine.  

 

AFM/DFM comparision:

 

https://gm-techlink.com/?p=11880

[leftynmn]

I had a 2014 GMC all terrian with DFM, 6 speed. Horrible clunking in low gear shifting. Used a  Range tech 003 to get rid of the switching from V8 to V4. I now have a 2019 Chevy Trailboss LT 5.3. How do I know if this has DFM? As sites I have looked at says it is available on the Trailboss not standard. No where does it show it is going into V4 like my old GMC. How do I know if I have DFM on my 2019 Trailboss?

[14SLE]

Personally, I am not sure how you tell what system your engine has unless you have the original paperwork.

Your 2014 would definitely have been AFM (8 cylinder/4 cylinder).  I'm not positive, but I believe I read that 2019's with the 6-speed transmission still have AFM.  I believe my salesman said you could order either AFM or DFM with the higher trim levels.  My dealership only ordered DFM on trucks when it was available.  The DFM is definitely a major improvement--I just hope it holds up over the long term.  GM has had some bad engine experiments over time (350 diesel, Quad 4, 3.4L head gaskets, 3.6L timing chain, water-logged opti-spark systems, bad 305 camshafts, the list goes on...).

Edited January 27, 2021 by 14SLE
Added more info

[redwngr]

Prior to the T1's, they only used AFM. 

 

The 2019 K2 style double cab used the L83, which was an AFM 5.3L

L83	Engine, 5.3L EcoTec3 V8 with Active Fuel Management, Direct Injection and Variable Valve Timing, includes aluminum block construction (355 hp [265 kW] @ 5600 rpm, 383 lb-ft of torque [518 Nm] @ 4100 rpm; more than 300 lb-ft of torque from 2000 to 5600 rpm)

 

 

If you know which engine you have you know if it is AFM or DFM.

 

If it's a T1 truck,

the AFM 5.3 is the L82 .

L82

Engine, 5.3L EcoTec3 V8, (355 hp [265 kW] @ 5600 rpm, 383 lb-ft of torque [518 Nm] @ 4100 rpm)

 

the  DFM 5.3 is the L84. 

L84

Engine, 5.3L EcoTec3 V8, (355 hp [265 kW] @ 5600 rpm, 383 lb-ft of torque [518 Nm] @ 4100 rpm); featuring all-new Dynamic Fuel Management that enables the engine to operate in 17 different patterns between 2 and 8 cylinders, depending on demand, to optimize power delivery and efficiency

 

 

For the T1's, lower trims  -- WT, Custom, Custom TB, and the base Sierra, use the L82. 

The higher trims use the L84. 

No trim uses both.  

 

 

Edited January 27, 2021 by redwngr

[Tigerwitha88]

On 12/15/2020 at 9:52 PM, Kdn85 said:

Hey guys hope all is well, I’ve read and seen in my own walks of life that the old active fuel management equipped 5.3s had issues and curious to those who have 2019 5.3s and up with the new dynamic fuel management how’s it going with it? I have a 19 Silverado with dfm and so far so good at 15k miles. From what I’ve researched I know this is a very complex technology and had me a tad bit concerned for longevity of the engine but I didn’t know about this system  when I bought it  I’m hoping they did a good job and won’t have the issues the old AFM systems had. And again I’m loving the truck so far , very nice! Thanks. 

My advice by a Range and deactivate it.

[BossTaco2020]

My dad has a 2013 Sierra with the 5.3 and AFM and has had no problems at all with it. I can't tell what "pattern" I'm in with my 2020 Trail Boss either and so far no issues (~6000 miles).

[KARNUT]

I know 1 person who loved the 5.7 diesel in my family. That would be out of 4. The 3 others not so much. We had 3 6.5 diesels all junks gone by 100K, warranty ended. My mother drove the 94 Chevy 6.5 until 2000. Several injection pumps. Traded it for a 2000 Ford 7.3. Still driving it with 200K plus. Problem free. My father traded his problematic 95 Texas stagecoach 6.5 diesel dulley for a 98 Ram diesel. It’s been problem free. Drove it until he passed last year. Still going. Cylinder deactivation of any kind, nope.


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[A muz]

I hear everyone complain about the AFM but i never had an issue i asked Some mechanics about it , they told me its all about oil change never change at 10k km always at 5k and if u can change it at 4-4.5k km , have doing that for 6 years and not a single problem with the engine 5.3 6spd 2016 sierra with 220k km still going strong 

[newdude]

On 12/15/2020 at 9:52 PM, Kdn85 said:

From what I’ve researched I know this is a very complex technology and had me a tad bit concerned for longevity of the engine but I didn’t know about this system  when I bought it  I’m hoping they did a good job and won’t have the issues the old AFM systems had. And again I’m loving the truck so far , very nice! Thanks. 

 

Its really not any more complex than AFM.  The biggest differences being they ditched the VLOM for 8 individual cylinder lifter control solenoids and all 8 cylinders have active lifters.  Otherwise the basics of it are the same, ECM controlled cylinder deactivation just on any of all 8 cylinders at almost any time instead of just 4 that can deactivate.

[Justinv113]

One of my friends has over 70k miles on his 19 tb with a 5.3. Just had to get a new cam and lifter installed when the lifter failed. I'm not sure if it's as bad as the afm, but I'm not convinced the dfm is much better. Range device might be cheap insurance.