DFM disabler released

K5-Z71 · Sep 28, 2024

BacDoc said:
I was wondering about this - putting it in “Sport” or “Trailer” should disable the DFM?

Also my truck is new 2024 and I haven’t been able to detect any noises or shudder when the DFM activates. My boat with a 4-stroke Yamaha had a problem with the injectors and 2 of the 6 cylinders would “deactivate” intermittently and I could definitely hear it and feel the engine shudder until all cylinders kicked in.

There’s no user configuration which will disable DFM in these trucks ie sport, trailer, L9.

Apples and oranges between a Yammy v6 and these v8’s both in the method used to drop cylinders and primary / secondary balance effects.

Little evidence to show this is a modification to improve reliability of the system but it sure feels good to partially disable it.

BacDoc · Sep 28, 2024

nick14226 said:
L9 is the only way to disable.
I didn’t feel it with mine until about 5000 miles in. I hated AFM and thought wow the DFM is way better, and then I started feeling the lugging, vibration, etc just as bad if not worse than AFM. Not a fan.

With that said, wife’s blazer with the v6 drops cylinders and it’s not noticeable…

My truck is 2024 6.2l and only has 6k miles now.

I turn radio off and listen for a variety of rpm/ speed ranges and I have never heard or felt anything. I always turn off auto stop as that’s not really bad but no question when it is on, the stop and start is very annoying. Plus my wife is very sensitive and she would feel the pea in the 100 mattresses and she hasn’t noticed any thing lol!

I have a hard time believing that the DFM would engage in tow mode. Think that would have a higher failure rate.

Has any one reported engine failure/lifter issues with towing? I haven’t seen any on this forum.

nick14226 · Sep 28, 2024

K5-Z71 said:
There’s no user configuration which will disable DFM in these trucks ie sport, trailer, L9.

Apples and oranges between a Yammy v6 and these v8’s both in the method used to drop cylinders and primary / secondary balance effects.

Little evidence to show this is a modification to improve reliability of the system but it sure feels good to partially disable it.

L9 disables DFM, it’s in a service bulletin for troubleshooting and I can tell you it does. I don’t like the way it drives in L9 though, and losing 10th gear isn’t ideal either.

Right, but I’m saying there’s no vibration or lugging when the v6 drops cylinders. I don’t think the system belongs in v8’s, heavier vehicles, or whatever other variables are at play.

Doubt it helps reliability in terms of lifters, but overall happiness of an engine that lugs vs one that doesn’t, time will tell but I think it could help. It’s a drivability thing for me though more than anything.

BacDoc · Sep 28, 2024

K5-Z71 said:
There’s no user configuration which will disable DFM in these trucks ie sport, trailer, L9.

Apples and oranges between a Yammy v6 and these v8’s both in the method used to drop cylinders and primary / secondary balance effects.

Little evidence to show this is a modification to improve reliability of the system but it sure feels good to partially disable it.

Exactly right! Yamaha v6 is different but I can definitely notice the cylinder deactivation of 2/6. That’s the point I was trying to make. I never feel or hear anything from the Tahoe.

It’s not subtle and the engine didn’t sustain damage and compression was equal in all cylinders when mechanic checked it. I’m sure if I kept running it eventually I’d have engine failure.

nick14226 · Sep 28, 2024

BacDoc said:
My truck is 2024 6.2l and only has 6k miles now.

I turn radio off and listen for a variety of rpm/ speed ranges and I have never heard or felt anything. I always turn off auto stop as that’s not really bad but no question when it is on, the stop and start is very annoying. Plus my wife is very sensitive and she would feel the pea in the 100 mattresses and she hasn’t noticed any thing lol!

I have a hard time believing that the DFM would engage in tow mode. Think that would have a higher failure rate.

Has any one reported engine failure/lifter issues with towing? I haven’t seen any on this forum.

It engages in tow mode, L9 is the only way to disable in stock form.

BacDoc · Sep 28, 2024

nick14226 said:
It engages in tow mode, L9 is the only way to disable in stock form.

Well I maybe give the GM engineers too much credit. I would think enabling DFM in tow mode - that sets the engine up for failure. Higher temperatures and load on motor would seem like lugging a manual transmission.

Towing puts a lot of stress on motor and I tow 6500lbs couple times a month and mostly on a 10 mile stretch at 50 mph on cruise control. So far I haven’t heard or felt anything. 6.5k is not max but at cruise Im sure the DFM would kick in?

nick14226 · Sep 28, 2024

BacDoc said:
Well I maybe give the GM engineers too much credit. I would think enabling DFM in tow mode - that sets the engine up for failure. Higher temperatures and load on motor would seem like lugging a manual transmission.

Towing puts a lot of stress on motor and I tow 6500lbs couple times a month and mostly on a 10 mile stretch at 50 mph on cruise control. So far I haven’t heard or felt anything. 6.5k is not max but at cruise Im sure the DFM would kick in?

May not drop cylinders when you’re towing depending on weight, grade, speed, etc, but it’s not disabled in tow mode for this gen.

Coolman1987us · Sep 29, 2024

nick14226 said:
May not drop cylinders when you’re towing depending on weight, grade, speed, etc, but it’s not disabled in tow mode for this gen.

I don't think it was disabled on any of them in tow haul mode. Both my 08 and 13 went into AFM when in tow haul. Only thing that stops it is M5 (6 speed).

KMeloney · Sep 30, 2024

Any of you who installed this module also have the AutoStop Eliminator installed? Any conflict between the two with both modules installed?

nick14226 · Sep 30, 2024

KMeloney said:
Any of you who installed this module also have the AutoStop Eliminator installed? Any conflict between the two with both modules installed?

I do, no issues

DFM disabler released

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