5.3 Dynamic fuel management

[Grumpy Bear]

The truth is a hard thing to find and why, I suppose, it intrigues me. Often confused with facts. Considered opinion by some. Rarely defended and often criticized. But truth, it has power.

 

I find truth in three areas fairly easy to find; God, math and physics. That is if you go to the source and not the person manipulating them. As the last two are the result of the first….I find ‘it’ reliable. Who can question God?

Isaac Newton is sitting under a tree one day and an apple falls to the ground. He ponders this event and today we see the result of the meditation as the three laws of motion. Does that mean Newton invented Motion Law?

No. It had always existed. Isaac was just the first to understand it well enough to explain it. How? Was God ignorant of that law? Hardly. He created it. So the source is faithful.

 

Albert Einstein is contemplating a train and the perspectives of various observers. That meditation produced several Theories of Relativity. Theories solid enough to be used to send men to the moon. How?

Galilei Galileo drops two dissimilar balls off a famous leaning tower. Gravity calculations results from his meditation. Did he invent gravity? We still use those equations. Your ECU/PCM can’t operate without them. How?

 

The thing that connects God’s physical laws to the study of Physics is Math. That is how!  That is in explaining the workings of the natural world. Data is our friend. But only if you understand its significance and, and it’s a big AND, you don’t bend the math to suit your will. Back to Galileo and scientific method.

 

This the case the first thing people who hate the truth attack is the math. More precisely the measurement. Then the method and then….they just don’t want an answer.

 

Well I do and am quite content not to use the abstract to muddy the definite to irrelevance. That said I’m not oblivious to it either.

 

What does that mean? Means I’m not going to apply a rule of measurement intended for measurements in the field of quantum mechanics to cast a doubt about the accuracy of a GPS measured mile in calibrating my odometer. But I also see the need for a large enough sample size to relegate any unintended error in measurement to a decimal so small that it matters not. All I’m looking for is a ‘process capable’ value that can be used to compare one apple to another.

 

Data will tell the story, not the story teller.

[HPS]

I have a 2021 Silverado 1500 LT with the 5.3 Engine.  The window build sheet shows that it was equipped WITHOUT DFM and credited $50.  That is the ONLY reason that I bought this vehicle. There were some Silverado 1500 pickups built that way during the Covid period.

[Z45]

5 hours ago, HPS said:

I have a 2021 Silverado 1500 LT with the 5.3 Engine.  The window build sheet shows that it was equipped WITHOUT DFM and credited $50.  That is the ONLY reason that I bought this vehicle. There were some Silverado 1500 pickups built that way during the Covid period.

 

 

[quote]Some 2021 Silverado 1500 and Sierra 1500 trucks equipped with the 5.3L V8 engine (RPO L82) and 6L80 6-speed automatic transmission (RPO MYC) or the 5.3L V8 engine (RPO L84) (Fig. 19) and 8L90 8-speed automatic transmission (RPO MQE) may not have the Active Fuel Management/AFM (L82 engine) or Dynamic Fuel Management/DFM (L84 engine) feature. Beginning in March 2021, trucks produced without AFM or DFM are identified with RPO YK9 – Not Equipped with Cylinder Deactivation.

 

TIP: Any truck with RPO YK9 cannot be reprogramed and changed to turn on or activate the AFM/DFM functionality.

AFM can provide maximum fuel economy under light load driving conditions by deactivating engine cylinders 1, 7, 6, and 4, switching to a V4 mode.

DFM has the ability to deactivate any combination of cylinder valves, which allows for a large variety of firing sequences. The control of every cylinder event optimizes engine performance so that peak efficiency is obtained throughout the range of engine operation.

While diagnosing engine or electrical wiring concerns on these models, keep in mind that internal components related to AFM or DFM functions will be present in the engines as well as related wiring, connectors and fuses. The Engine Control Module (ECM) will not be capable of activating the cylinder deactivation technology.

When diagnosing and repairing concerns regarding engine or electrical functions that may be related to AFM- or DFM-related hardware, follow the diagnostics in the appropriate Service Information. No changes have been made to AFM- or DFM-related components.

For additional information, refer to #21-NA-078.[/quote]

Edited April 10, 2024 by elcamino

[AirMech74]

Has anyone with a '24 5.3L with DFM had any issues that were directly related to DFM?  I got mine in late July of 24, just about to hit 7K miles. I can't compare to any other models as this is my first GMC...but I feel it drives pretty smooth especially on the highways at higher speeds and I don't really notice anything when driving at lower speeds in the city. Unfortunately, I didn't know anything about AFM/DFM when I went in to buy my truck...I just knew I didn't want the 6.3L and the 3.0 doesn't fit my driving style. Mainly in city driving.

[KARNUT]

55 minutes ago, AirMech74 said:

Has anyone with a '24 5.3L with DFM had any issues that were directly related to DFM?  I got mine in late July of 24, just about to hit 7K miles. I can't compare to any other models as this is my first GMC...but I feel it drives pretty smooth especially on the highways at higher speeds and I don't really notice anything when driving at lower speeds in the city. Unfortunately, I didn't know anything about AFM/DFM when I went in to buy my truck...I just knew I didn't want the 6.3L and the 3.0 doesn't fit my driving style. Mainly in city driving.

It seems other manufacturers have been having luck with cycling deactivation. I’m approaching 158K with an Odyssey with it. The on light is on most times unlike my GM truck with it. I suspect GM has a problem with hard parts more than the technology. I just recently read an article that almost 1 million 6.2s may be recalled due to bad main bearings.

[15 Z71]

3 hours ago, AirMech74 said:

Has anyone with a '24 5.3L with DFM had any issues that were directly related to DFM?  I got mine in late July of 24, just about to hit 7K miles. I can't compare to any other models as this is my first GMC...but I feel it drives pretty smooth especially on the highways at higher speeds and I don't really notice anything when driving at lower speeds in the city. Unfortunately, I didn't know anything about AFM/DFM when I went in to buy my truck...I just knew I didn't want the 6.3L and the 3.0 doesn't fit my driving style. Mainly in city driving.

I would just drive it. I had a 2015 with it and sold it with a 129,000 on it bone stock. All I read was better turn it off or get a catch can or you will have problems. Nope not one. I sold it to a kid up the street he still driving it with no issues. 

[silveradosid]

my 2014 had 160k miles on it when i sold it to my son, he called me the other day all excited about it turning 200k with the original engine and tranny. only did the pill flip for the tranny and used a range device.