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Username Post: Dynamic Fuel Management        (Topic#368290)
supertug 
"6th Year" Platinum Supporting Member
Posts: 212
supertug
Loc: Georgia
Reg: 05-03-06
04-29-22 07:34 AM - Post#2840445    

Good morning all. I am trying to determine if the 2019 through 2021 Tahoe/Yukon has dynamic fuel management. The info I have found so far, and have only just started this morning, is limited. With all of the reported problems with Active Fuel Management (AFM), I would like to stay away from AFM if possible. I appreciate all input and any opinions on if the AFM has been improved. Thanks.



Edited by supertug on 04-29-22 05:07 PM. Reason for edit: No reason given.

 
elcamino 
Dedicated Member
Posts: 5547
elcamino
Loc: Lake Superior-Michigan US...
Reg: 03-30-00
04-30-22 09:30 AM - Post#2840490    
    In response to supertug

Source is GM
2019 has Active Fuel Management
2020-2022 has Dynamic Fuel Management


AFM shuts down the same cylinders
DFM shuts down up to 6 at any one time and all are subject to it, not just the same 4 as with AFM.

IMO neither is any good but the only way for GM to keep V8 engines and improve EPA mileage estimates,


Mike
2021 GMC 4WD Sierra Denali CC 6.2L/10-sp
2018 Polaris RZR S 900 EPS
2017 John Deere X738 Snow Blower


 
supertug 
"6th Year" Platinum Supporting Member
Posts: 212
supertug
Loc: Georgia
Reg: 05-03-06
05-01-22 09:41 AM - Post#2840526    
    In response to elcamino

As best as I am able to determine, in 2020 DFM was only available on the Sierra & Silverado engines with the 8 or 10 speed transmissions. I am looking at a 2020 Tahoe with the 5.3 and 6 speed transmission. If we purchase one then we will go with a disabler device.



 
Tony1963 
Frequent Contributor
Posts: 1283

Loc: Orlando Florida
Reg: 07-09-18
05-01-22 01:13 PM - Post#2840541    
    In response to supertug

Keep in mind that the drivetrain was designed with all of those parts functional. Inhibiting the design is not only a violation of emissions standards, it can void the warranty and also cause other vehicle issues. For instance, the catalytic converter was designed with a certain amount of useful life and if you are forcing more exhaust gasses than designed, you'll not save anything.

Use the system as designed. Why people want to disable technology is beyond me?



 
1983G20Van 
Super Senior Member
Posts: 3914

Loc: Hurst, Texas, USA
Reg: 11-13-02
05-02-22 05:55 PM - Post#2840594    
    In response to Tony1963

  • Tony1963 Said:
Keep in mind that the drivetrain was designed with all of those parts functional. Inhibiting the design is not only a violation of emissions standards, it can void the warranty and also cause other vehicle issues. For instance, the catalytic converter was designed with a certain amount of useful life and if you are forcing more exhaust gasses than designed, you'll not save anything.

Use the system as designed. Why people want to disable technology is beyond me?



Technology that is garbage like the 8-6-4 Cadillacs. Best to disable it for the long run, same with the Start/Stop garbage. I have seen one with these lifters fail in a brand new 100K Denali a few weeks ago at 2,600 miles! Garbage and Junk is what it is. As far as forcing more gases through the cat, not at all. The same amount of exhaust is still going through the cats its just going through less cylinders. Its a gimick at best and one of the reasons I have a 2019 Titan instead of a GM. I get better than 22 mpg highway on all 8 all the time. The AFM/DFM engines load the cylinders more heavily than a normal V8 causing added wear and oil consumption.

1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals


Edited by 1983G20Van on 05-02-22 05:57 PM. Reason for edit: No reason given.

 
Tony1963 
Frequent Contributor
Posts: 1283

Loc: Orlando Florida
Reg: 07-09-18
05-04-22 04:23 AM - Post#2840671    
    In response to 1983G20Van

I have seen people along the side of the road with flat tires, too. However, I don't abandon tire technology because of a low frequency failure.

With regard to the catalyst, running all cylinders all of the time produces more exhaust gasses than running some of the cylinders. If the design included a lower volume of exhaust gasses due to the cylinder deactivation, then you are probably going to have a catalyst failure sooner. That is an expensive repair.

As far as the Cadillac 8-6-4, it used entirely different technology to disable the cylinders. Yes, it had issues but nothing like the folk lore has created. I've owned these cars in the past and the only thing that I noted that people could object was that in 6-cylinder mode, there is a bit of an erratic engine due to it running in 6-cylinder mode and having somewhat of a uneven firing order. However, the 6-cylinder mode is usually only a few seconds as it transitions to 4- cylinder mode.

There is always a difference between "perception" and "facts".

However, do as you see fit. That is the beauty of ownership.



 
BigDogSS 
"13th Year" Silver Supporting Member
Posts: 5042
BigDogSS
Loc: SoCal
Reg: 12-21-01
05-06-22 09:07 AM - Post#2840778    
    In response to Tony1963

I have a couple of close friend with trucks that have the AFM where the lifters failed and came apart. One was fixed under warranty, the other was out of warranty and destroyed the engine. I'm rethinking a future purchase of GM trucks because of this issue. And these are firsthand "facts".
I actually have no problem with the start-stop technology.

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



Edited by BigDogSS on 05-06-22 09:08 AM. Reason for edit: No reason given.

 
BigDogSS 
"13th Year" Silver Supporting Member
Posts: 5042
BigDogSS
Loc: SoCal
Reg: 12-21-01
05-09-22 08:01 AM - Post#2840922    
    In response to BigDogSS

Another point: I'm speculating that MOST of these failures happen at over 100K miles and they are out of warranty. I feel because of these two facts (my view), GM sees these failures as "acceptable".
I personally do not want to deal with this issue on my next truck purchase...

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



 
Tony1963 
Frequent Contributor
Posts: 1283

Loc: Orlando Florida
Reg: 07-09-18
05-09-22 11:59 AM - Post#2840933    
    In response to BigDogSS

No one wants to deal with these issues. However, I am not certain that deactivating the active or dynamic fuel management will save you anything if it leads to other failures.

Case in point - I have a Mercedes convertible that needed one of the interior air temperature sensors changed. It was a bit of work to take the overhead console apart and change the sensor, but the system relies upon several sensing points to function as designed.

New sensor for $22 and all is well.





 
BigDogSS 
"13th Year" Silver Supporting Member
Posts: 5042
BigDogSS
Loc: SoCal
Reg: 12-21-01
05-09-22 02:06 PM - Post#2840938    
    In response to Tony1963

  • Tony1963 Said:
... However, I am not certain that deactivating the active or dynamic fuel management will save you anything if it leads to other failures. ....


That is the point...the part of the AFM/DFM that fails is the lifters. Deactivating the system electronically does nothing to "fix" the problem if the same failure-prone lifters are not changed to regular lifters


    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



 
elcamino 
Dedicated Member
Posts: 5547
elcamino
Loc: Lake Superior-Michigan US...
Reg: 03-30-00
05-09-22 04:06 PM - Post#2840944    
    In response to BigDogSS

I have one of those DFM trucks where the lifter colapsed at 11,400 miles. Left bank, driving along at 55 and heard a noise. Thought I rode over something on the road but soon came to a stop sign and engine was stumbling and warnings lights on the dash. I was one mile for the GMC Dealer so I drove i into the service bay. Tech started it up and said, yup, collapsed lifter. What was astounding, its such a common problem they had all the parts in stock.

2021 Sierra Denali 6.2L, now has 15,400 miles.



Mike
2021 GMC 4WD Sierra Denali CC 6.2L/10-sp
2018 Polaris RZR S 900 EPS
2017 John Deere X738 Snow Blower


 
BigDogSS 
"13th Year" Silver Supporting Member
Posts: 5042
BigDogSS
Loc: SoCal
Reg: 12-21-01
05-11-22 12:43 PM - Post#2841046    
    In response to Tony1963

  • Tony1963 Said:
Keep in mind that the drivetrain was designed with all of those parts functional. Inhibiting the design is not only a violation of emissions standards, it can void the warranty and also cause other vehicle issues. For instance, the catalytic converter was designed with a certain amount of useful life and if you are forcing more exhaust gasses than designed, you'll not save anything.

Use the system as designed. Why people want to disable technology is beyond me?


Apparently, GM says it is OK to disable the DFM. According to another forum, the DFM lifters are still in the engine.



Attachment: Silverado_DFM.JPG (202.67 KB) 4 View(s)




    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



Edited by BigDogSS on 05-11-22 12:45 PM. Reason for edit: No reason given.

 
Tony1963 
Frequent Contributor
Posts: 1283

Loc: Orlando Florida
Reg: 07-09-18
05-11-22 01:15 PM - Post#2841050    
    In response to BigDogSS

The invoice says that the engine does not have the dynamic fuel management system, therefore, the lifters are not the same.



 
BigDogSS 
"13th Year" Silver Supporting Member
Posts: 5042
BigDogSS
Loc: SoCal
Reg: 12-21-01
05-11-22 03:11 PM - Post#2841057    
    In response to Tony1963

Maybe. Reading on some other forums specific to Silverados state the lifters are the same and GM merely turned off the DFM electronics due to the chip shortage.

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



Edited by BigDogSS on 05-11-22 03:12 PM. Reason for edit: No reason given.

 
elcamino 
Dedicated Member
Posts: 5547
elcamino
Loc: Lake Superior-Michigan US...
Reg: 03-30-00
05-11-22 05:46 PM - Post#2841065    
    In response to Tony1963

All the DFM components are in the engine, just not the chips to make it work. I read that it takes a lot computer chips to run the AFM/DFM.

  • Quote:

Changes to the AFM and DFM Feature on 2021 Silverado 1500 and Sierra 1500
March 30, 2021

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.







Mike
2021 GMC 4WD Sierra Denali CC 6.2L/10-sp
2018 Polaris RZR S 900 EPS
2017 John Deere X738 Snow Blower


 
Tony1963 
Frequent Contributor
Posts: 1283

Loc: Orlando Florida
Reg: 07-09-18
05-11-22 07:21 PM - Post#2841072    
    In response to elcamino

Well, there ya go. All of the parts are there except the brains to run the system. You are correct.



 
BigDogSS 
"13th Year" Silver Supporting Member
Posts: 5042
BigDogSS
Loc: SoCal
Reg: 12-21-01
05-12-22 09:31 AM - Post#2841098    
    In response to elcamino

Thank you, Mike!

    1967 Chevrolet Impala SS convertible 327 - Ermine White C1 - VCCA Senior Award
    1967 Chevrolet Impala SS Sport Coupe 396 - Marina Blue FF - personal "barn-find" lol



 
dgstarr 
"4th Year" Silver Supporting Member
Posts: 310
dgstarr
Loc: Portland, OR
Reg: 04-16-13
05-14-22 03:17 PM - Post#2841206    
    In response to elcamino

I have a 2021 Silverado 1500, 5.3 with DFM. I changed the oil at 2000 mi, 6000 miles, and 9800 miles using Mobil One 0W20 Dexos oil as recommended. I had deactivated the DFM with A Range. A lifter failed and bent a pushrod at 9900 miles. GM replaced all the lifters and one pushrod under warranty. Mine was assembled during the period when the lifters were known to be defective (Sep 20-Mar 21). Lifters installed outside of this window have also failed, but not as often. If you want a bullet proof GM pickup engine, buy a 2500. Don't waste your money on cylinder deactivation.



 
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