Disabling GM Active Fuel Management

[East30]

Curious if anyone has disabled their AFM (Active Fuel Management) on their Chevy or GMC trucks. I purchased a 2021 Silverado during the chip shortage in the days of Covid chip shortages. I really liked that my Silverado did not have the AFM as they didn't have enough chips to activate it. Just bought a 2025 and now AFM is again enabled on all 5.3L engines and would like to disable it.

Wondering if anyone has tried this disabler: https://www.rangetechnology.com/products/afm-dfm_disabler/

I didn't seem to take a noticeable hit on mileage without the feature. I also had issue with previous Chevy's using oil with this feature enabled, as compression increases on those 4 cylinders, causing oil consumption as I was told by service technicians. Two previous Silverado's both used more oil. One, so much, that Chevrolet gave me a discount coupon to purchase a new Silverado. I would also feel much more vibration at stop, as it was idling on only four cylinders; stop lights and such. I don't notice that on my new 2025. Yet.

Thanks for any info that may be provided.

 

[TractorTYMe]

It should work ok, but the best would be to do an all out delete of the lifters and such to increase reliability. But I had a Pontiac G8GT with an L76 with this system, and I had it disabled in a tune. And it never gave me any oil consumption problems.

 

[deezler]

The range chips to disable AFM work very well. No issues. A couple of my coworkers routinely trade up through GMC/Chevy 5.3L 1500s and always buy the range chip to disable AFM/DFM.

If it were my truck..... I'd be doing an aftermarket ECU tune that increased HP and responsiveness as well.

 

[deezler]

I would also feel much more vibration at stop, as it was idling on only four cylinders; stop lights and such. I don't notice that on my new 2025. Yet.

I will say that GM vastly improved their cylinder deactivation strategy with their new DFM (dynamic fuel management). Instead of the same 4 cylinders turning off with the old AFM, the new DFM strategy continuously cycles through all 8 cylinder of the engine in as many as 17 different patterns, with anywhere from 2 to 8 cylinders running. But each individual cylinder never stays off for long, coming back on quickly to stay warm, keep the rings moving, avoid oil consumption issues, etc.

That said, it's a complexity adder who's only benefit is a 0.1 or maybe 0.5 mpg benefit. I would still disable it myself, but not as critical to do so vs the old AFM.

 

[Lineman North Florida]

I disabled it on a 2011 GMC Yukon that my wife used to have, when we got rid of it, it had over 250k miles on it with no issues, also disabled it on a 2012 Silverado 4x4 that I still own with over 200k on it and no problems, there is a cheaper one on Amazon than the Range and it does the same thing.

 

[ruffdog]

I have a Range disabler in my 2013 and it works fine. It will run the battery down if you don't drive much. You can get a extension wire for it that has an on/off switch. Most of my driving is local back roads so I shift into M5 which keeps it in v8 mode without using the Range.

 

[Hay Dude]

When did AFM start? My sons looking at a very clean, rust free 2006 5.3L with only 94K miles.
I thought it started 2007?

 

[Cub 7275]

Got two 5.3 with AFM. 2011 with 138K and a 2013 with 186K. I looked at the Range gizmo but there were complaints that it drained the battery if the vehicle is parked for extended periods, as mine can be. Just the fact that it draws that much power all the time (or keeps other modules from going to sleep causing the extra power draw) was a turnoff. A Diablo sport tuner was used to shut off the AFM on the 2013 because of the high mileage and not knowing its history with the previous owner(s). My main reason for disabling AFM was to prevent lifter failure where the lifter collapses when AFM is activated, but it doesn't pump back up when commanded to.

 

[Wolverinefarm22]

Free way to get around it is to put the gear selector in L and manually go to the highest gear. It disables afm or dfm and drives like normal.

 

[Cub 7275]

Maybe that works with the newer ones, but on a 2013, like ruffdog said, M5 will disable it. Select M6 and AFM is active. I believe the 2011 is the same.

 

[riptides]

When did AFM start? My sons looking at a very clean, rust free 2006 5.3L with only 94K miles.
I thought it started 2007?

https://www.silveradosierra.com/threads/what-year-was-afm-introduced-into-silverado-sierras.659041/

 

[East30]

Update, I did find that the disabler I posted at the start does not work on the 2025 Silverado I purchased.

I would need this one: https://www.rangetechnology.com/products/afm-dfm_disabler/parts/RA007
It's new. I called and they stated it was just finished testing in the last couple of weeks. So it's really new.

It has a bonus in that it also disables the auto start/stop feature, which I've always disliked.

 

[dodge man]

My opinion on AFM relates to how it works on Chrysler products. Hemi engines have had it for several years on cars and trucks both. They call it MDS, multi displacement system. It does work well for saving fuel but much better in cars than trucks. I’ve got a 2010 Challenger that I turned it off on. I’ve had a truck that had it also and we have a 2019 Chrysler 300c that has it.

Programming has a lot to do it. Our newer 300c is so much better. It isn’t constantly trying to go into 4 cylinder mode and as you approach 75mph it just stays running on 8 cylinders. On the Ram we had, a 2007 I think, it just cut so much wind on the highway it was constantly trying to switch in and out of 4 cylinder mode.

On my Challenger the programming was so annoying, it was just constantly switching on and off. When I turned it off I was shocked how much it affected fuel mileage. I’d say it was at least 10% worse. It’s a 15 year old car with 24,000 miles on it so the hit on mpg is meaningless to me.

 

[TheGoose]

I have the range for 2018 vintage Silverados and it works as advertised. Never noticed a drop in mileage , actually think it got slightly better if anything.

 

[5030]

Disabling the GM AFM entirely depends on the year of manufacture actually. Some can be done with an add on module, some have to be mechanically deleted. All BS as far as I'm concerned and all contribute to burning oil from dried out cylinders.

 

[ruffdog]

Disabling the GM AFM entirely depends on the year of manufacture actually. Some can be done with an add on module, some have to be mechanically deleted. All BS as far as I'm concerned and all contribute to burning oil from dried out cylinders.

The oil burning was not caused by dried out cylinders. The problem was too much oil being sprayed at the piston skirts from the AFM pressure relief valve. Too much oil then would overload the oil control rings and create problems with the PCV system. Both would lead to oil consumption. Those issues were addressed in ~2011. They relocated the pressure relief valve, installed a shield, changed the valve cover design (PCV).

 

[5030]

The oil burning was not caused by dried out cylinders. The problem was too much oil being sprayed at the piston skirts from the AFM pressure relief valve. Too much oil then would overload the oil control rings and create problems with the PCV system. Both would lead to oil consumption. Those issues were addressed in ~2011. They relocated the pressure relief valve, installed a shield, changed the valve cover design (PCV).

Whatever. All I know is my wife's 2016 Suburban LTZ was using oil at rate of a quart every 500 miles and I did the mechanical delete on it and the oil consumption immediately stopped and her overall fuel mileage (not that it was ever good) didn't change a bit.

The ONLY reason why GM did it as to increase their CAFE to comply with the gummit.

Early models can be deleted electronically but some cannot. All depends on the year, displacement and how good you are at being a shadetree mechanic.

Now, other than normal oil consumption ( all internal combustion engines consume a bit of lube oil), it stays full or close to full between oil changes.

...and the oil and filter gets changed every 5, not 10 and it gets my usual Nano Borate additive as well at a rate of 1 fluid ounce per quart of oil.