New 2023 5.3 with DFM.

Jimbeau · July 31, 2023

Apparently GM is back in full swing manufacturing new 5.3’s with Dynamic Fuel Management (DFM), which shuts down cylinders randomly.

I’m not at all thrilled to learn that my brand new 2023 GMC 1500 came with DFM. For some reason I thought this was a thing of the past. It certainly wasn’t mentioned by the salesperson, or any marketing adds! It is on the window sticker, but definitely not something that jumps out at the customer.
Wasn’t this a huge problem? Please tell me GM has corrected the issues with this nonsense??? I call it nonsense because the fuel economy hasn’t even improved in my experience.
I have major concerns about reliability with this DFM system. The main reason I chose the V8 is for dependability, not fuel economy.

I typically keep my work trucks a long time and put over 200K on the odometer before selling. Is this going to be an issue?

Thanks!

diyer2 · July 31, 2023

I would suggest more frequent oil changes. 5K miles.

jaxcam02 · July 31, 2023

Every single new v8 engine on this planet is going to come with some form of DFM/DOD due to Big Brother Government. The only ones that won't are going to be performance vehicles, mostly supercharged like the ZL1. During the Covid supply chain and chip shortage, there were some trucks that were not manufactured with the chip but all the engines still had the internal components for DFM, specifically the DFM lifters. TBH, the whole failing lifter thing has been a bit overblown via the loud minority on the internet. IF, something ever happens to yours, you have a warranty. If it happens outside of warranty, I would say thats a perfect time to bust open the engine and install a camshaft and replace all the lifters with non-DFM lifters and remove all the DFM stuff yourself. I am one of the lucky ones that bought a covid truck without DFM so all I will need to do is pop off the heads and change to non-DFM lifters at some point.

newdude · July 31, 2023

9 hours ago, Jimbeau said:

Apparently GM is back in full swing manufacturing new 5.3’s with Dynamic Fuel Management (DFM), which shuts down cylinders randomly.

I’m not at all thrilled to learn that my brand new 2023 GMC 1500 came with DFM. For some reason I thought this was a thing of the past. It certainly wasn’t mentioned by the salesperson, or any marketing adds! It is on the window sticker, but definitely not something that jumps out at the customer.
Wasn’t this a huge problem? Please tell me GM has corrected the issues with this nonsense??? I call it nonsense because the fuel economy hasn’t even improved in my experience.
I have major concerns about reliability with this DFM system. The main reason I chose the V8 is for dependability, not fuel economy.

I typically keep my work trucks a long time and put over 200K on the odometer before selling. Is this going to be an issue?

Thanks!

DFM was always there really, never left the chat. Yes there was the trucks built with the chip shortage but that was late 2021 and most of 2022 model year. All 6.2s never lost DFM, and all 5.3s ordered with NHT max trailer had DFM during this time.

So far they must have fixed something as I've not seen any low mile 2022 or 2023 with DFM enabled come in for any lifter failures yet. We haven't opened up a 5.3 for maybe a year and a half now? The ones we did were in that bad window they had for 2021 model year.

Biggest thing IMO is shorten your oil changes. 3000mi minimum, 5000mi max.

Edited July 31, 2023 by newdude

Jimbeau · July 31, 2023

3 hours ago, diyer2 said:

I would suggest more frequent oil changes. 5K miles.

Thanks. Unfortunately I have read that this is particularly important for DFM engines. Synthetic I’m assuming?

Edited July 31, 2023 by Jimbeau

Jimbeau · July 31, 2023

2 minutes ago, newdude said:

DFM was always there really, never left the chat. Yes there was the trucks built with the chip shortage but that was late 2021 and most of 2022 model year. All 6.2s never lost DFM, and all 5.3s ordered with NHT max trailer had DFM during this time.

So far they must have fixed something as I've not seen any low mile 2022 or 2023 with DFM enabled come in for any lifter failures yet.

Biggest thing IMO is shorten your oil changes. 3000mi minimum, 5000mi max.

Thank you sir!!

Jimbeau · July 31, 2023

11 minutes ago, jaxcam02 said:

Every single new v8 engine on this planet is going to come with some form of DFM/DOD due to Big Brother Government. The only ones that won't are going to be performance vehicles, mostly supercharged like the ZL1. During the Covid supply chain and chip shortage, there were some trucks that were not manufactured with the chip but all the engines still had the internal components for DFM, specifically the DFM lifters. TBH, the whole failing lifter thing has been a bit overblown via the loud minority on the internet. IF, something ever happens to yours, you have a warranty. If it happens outside of warranty, I would say thats a perfect time to bust open the engine and install a camshaft and replace all the lifters with non-DFM lifters and remove all the DFM stuff yourself. I am one of the lucky ones that bought a covid truck without DFM so all I will need to do is pop off the heads and change to non-DFM lifters at some point.

Good points for sure. Definitely helps put this in perspective.
In my limited research I’m only finding problem trends with GM’s version of cylinder management. Hopefully it’s not as common as it appears.

Jimbeau · July 31, 2023

First of all I’m no auto mechanic. I am however a licensed aircraft mechanic with a good amount of piston, and jet engine background. In my business we never sacrifice dependability for economic reasons. This is quite different from today’s auto industry’s requirements.

Here’s where I am on the topic...

DFM: I know the subject itself has been beaten to death but I’m not seeing much information about the DFM relaunch (post chip) phase. Possibly a good thing that all is quiet!

Background: As I understand, the system was originally called AFM before transitioning into the more advanced DFM. Then, during the shortage, trucks were being sold with the system deactivated. Still installed, just deactivated, which sounds like a nightmare of engine parts not being used for their designed purpose, but that’s another subject.

2023: DFM production is apparently back in full swing now and we are not seeing much information in regards to it’s current dependability status. Considering the history, it seems that this subject would be actively monitored at a high level, especially among truck enthusiasts.

It’s great to hear from folks with the experience in this area and in the business. Thanks!!!
It would also be great to get feedback from those who have put some hard miles on the newly reactivated 5.3 with “operational” DFM.

Thank you much!

KARNUT · July 31, 2023

1 hour ago, Jimbeau said:

First of all I’m no auto mechanic. I am however a licensed aircraft mechanic with a good amount of piston, and jet engine background. In my business we never sacrifice dependability for economic reasons. This is quite different from today’s auto industry’s requirements.

Here’s where I am on the topic...

DFM: I know the subject itself has been beaten to death but I’m not seeing much information about the DFM relaunch (post chip) phase. Possibly a good thing that all is quiet!

Background: As I understand, the system was originally called AFM before transitioning into the more advanced DFM. Then, during the shortage, trucks were being sold with the system deactivated. Still installed, just deactivated, which sounds like a nightmare of engine parts not being used for their designed purpose, but that’s another subject.

2023: DFM production is apparently back in full swing now and we are not seeing much information in regards to it’s current dependability status. Considering the history, it seems that this subject would be actively monitored at a high level, especially among truck enthusiasts.

It’s great to hear from folks with the experience in this area and in the business. Thanks!!!
It would also be great to get feedback from those who have put some hard miles on the newly reactivated 5.3 with “operational” DFM.

Thank you much!

I’ve owned and ridden in cylinder deactivation vehicles. I now have a cylinder deactivation Odyssey. It’s a 2016 with 132k miles. It’s the first I can’t tell but by a light that’s is working. Amazing at 72 miles per hour on the freeway it’s on far more than off, contrary to my last GM truck. At that mph it was on only downhill. If it makes 200K miles not hard for a Honda. I’ll be a fan. For a vehicle that size to hover around 27 miles per gallon. It’s working as designed.

dieselfan1 · July 31, 2023

1 hour ago, KARNUT said:

I’ve owned and ridden in cylinder deactivation vehicles. I now have a cylinder deactivation Odyssey. It’s a 2016 with 132k miles. It’s the first I can’t tell but by a light that’s is working. Amazing at 72 miles per hour on the freeway it’s on far more than off, contrary to my last GM truck. At that mph it was on only downhill. If it makes 200K miles not hard for a Honda. I’ll be a fan. For a vehicle that size to hover around 27 miles per gallon. It’s working as designed.

This is a GM truck forum.

Not a honda mini van forum.

Quit comparing your non GM vehicles to GM vehicles. It's getting old.

This is where you should be.

https://www.odyclub.com/

Edited July 31, 2023 by dieselfan1

KARNUT · July 31, 2023

30 minutes ago, dieselfan1 said:

No need to be here.

When you buy a 2019- 2023 let's talk . So FO dumbass.

I read threads as they roll. The only people who get their panties in a wad are the ones who are overextended. And can’t fade the heat. I point out that some manufacturers have it figured out. I’ll never buy a Honda until they’re quieter on the road. Something GM does right. If you’ve read my threads you know the story behind the Hondas I’ve had. Pointing out flaws leads to improvements. Blindly throwing down money for inferior products doesn’t lead to improvement. I will buy rebuild and stay buying the best year model runs from GM. My old GM so far for almost 4 years has been trouble free. If you don’t like my response don’t read them Lone Ranger. Dummy.

Edited July 31, 2023 by KARNUT

newdude · July 31, 2023

4 hours ago, Jimbeau said:

Background: As I understand, the system was originally called AFM before transitioning into the more advanced DFM. Then, during the shortage, trucks were being sold with the system deactivated. Still installed, just deactivated, which sounds like a nightmare of engine parts not being used for their designed purpose, but that’s another subject.

Not the first time GM has assembled Gen 5 small blocks that have AFM/DFM lifters but are inactive. The supercharged LT4 had AFM active in the 2014-2019 Corvette and in the 2015-2020 CTS-V, but the Camaro ZL1 from 2017-current does NOT have AFM active. Same exact engine off the same assembly line so all of the hard parts are still in there.

There are only 3 engines in the trucks currently used that don't have AFM or DFM parts at all in them. The L8T 6.6 gas in the HD trucks and vans, the LT4 in the Escalade-V, and the LV1 variant of the 4.3 V6 found in Express and Savana.

Edited July 31, 2023 by newdude

dieselfan1 · July 31, 2023

I have more knowledge about GM trucks than you know. Over three million miles worth. You know more about old dodge diesels than me. And Hondas

KARNUT · July 31, 2023

19 minutes ago, dieselfan1 said:

I have more knowledge about GM trucks than you know. Over three million miles worth. You know more about old dodge diesels than me. And Hondas

I know the information I want to know. I pulled with 3/4 and 1 tons with my business over 1 million miles. I was fleet buyer for my family business. GM trucks weren’t good for pulling during the 80s-90s when I was pulling. Most fleet buyers I see buy Fords then Rams. When I started driving 1/2 tons I had a 98 ford XLT sport that I installed a s/c on. Then a 01 GMC 02 ford 04 z71 06 trailblazer ss 07 avalanche 08 ram. Then I went used do to the 08 economy reset. 98 two door Tahoe 98 ford lariat. 1964 el Camino. I then found a clean 92 Chevy lowered 383 with a whipple. December of 2013 a GMC Texas Edition my first cylinder deactivation truck for retirement. That doesn’t count the toys, wife cars and toys or fleet buys. The 14 GMC was a bust. 15 Santa Fe, 17 Camry, 02 Avalanche, CRV, odyssey during my almost 10 years retirement not counting wife car and toys. Yeah so I probably have little knowledge of new GMs and there’s a reason for that.