DFM disabler released

[JasonHTX]

I’m a beta tester, 100% worth it if you’re like me and the DFM causes noticeable lugging/vibration when maintaining speed or slight throttle tip in. I absolutely hate driveability with AFM/DFM on the v8’s. Wifes AFM on her v6 blazer on the other hand, don’t even notice it.

Install was very easy, not as easy as an OBD plug in, but super simple.

A couple questions:

1. Does it disable DFM at very low speeds like at a stop sign? I was reading on an AT4 forum that DFM is enabled at very slow speeds with the RA007 device.
2. Were you able to do the install without removing the tire? This is me just being lazy

Just ordered it from Range, but I was hoping you could shed some light on the two questions.

 

[nick14226]

A couple questions:

1. Does it disable DFM at very low speeds like at a stop sign? I was reading on an AT4 forum that DFM is enabled at very slow speeds with the RA007 device.
2. Were you able to do the install without removing the tire? This is me just being lazy

Just ordered it from Range, but I was hoping you could shed some light on the two questions.

My beef with DFM is cruising and slight throttle tip in, that's when I notice the lugging/shuddering/vibration. The range disabler stops all that.

Without the disabler, when coasting down to a stop or braking, the DFM is enabled and with a louder exhaust you'll hear the DFM then disable at 14 MPH because you can hear the cylinders activate with the exhaust getting louder. At idle all 8 are firing.

With the disabler installed I still hear that happening. So I would agree, at least on my rig, that the DFM is not disabled when braking or coasting down to a stop but is disabled at all other times. I mentioned this to Range when testing and they said some behave this way and some don't. I'm again happy, that coast down and braking never bothered me in the least because I can't feel it, just hear it. But as far as 100% disabled at all times, at least on my rig, don't think it is.

On my Z71 with the 3" readylift I cranked the wheel all the way to the left, pulled back on the fender liner, and was able to install it.
With other trims it may be trickier if the fender liner sits lower than the Z71.
And the 3" lift gives more space.
But with all that said I think even stock non-Z71 it's probably doable this way, maybe just have to remove a couple of the fender liner screws.

 

[JasonHTX]

My beef with DFM is cruising and slight throttle tip in, that's when I notice the lugging/shuddering/vibration. The range disabler stops all that.

Without the disabler, when coasting down to a stop or braking, the DFM is enabled and with a louder exhaust you'll hear the DFM then disable at 14 MPH because you can hear the cylinders activate with the exhaust getting louder. At idle all 8 are firing.

With the disabler installed I still hear that happening. So I would agree, at least on my rig, that the DFM is not disabled when braking or coasting down to a stop but is disabled at all other times. I mentioned this to Range when testing and they said some behave this way and some don't. I'm again happy, that coast down and braking never bothered me in the least because I can't feel it, just hear it. But as far as 100% disabled at all times, at least on my rig, don't think it is.

On my Z71 with the 3" readylift I cranked the wheel all the way to the left, pulled back on the fender liner, and was able to install it.
With other trims it may be trickier if the fender liner sits lower than the Z71.
And the 3" lift gives more space.
But with all that said I think even stock non-Z71 it's probably doable this way, maybe just have to remove a couple of the fender liner screws.

Thanks! Yeah, I have the air suspension on the Denali, so I will try and put it in service mode (highest setting) to see if I can get it done w/o removing the tire.

Appreciate the help!

 

[JasonHTX]

My beef with DFM is cruising and slight throttle tip in, that's when I notice the lugging/shuddering/vibration. The range disabler stops all that.

Without the disabler, when coasting down to a stop or braking, the DFM is enabled and with a louder exhaust you'll hear the DFM then disable at 14 MPH because you can hear the cylinders activate with the exhaust getting louder. At idle all 8 are firing.

With the disabler installed I still hear that happening. So I would agree, at least on my rig, that the DFM is not disabled when braking or coasting down to a stop but is disabled at all other times. I mentioned this to Range when testing and they said some behave this way and some don't. I'm again happy, that coast down and braking never bothered me in the least because I can't feel it, just hear it. But as far as 100% disabled at all times, at least on my rig, don't think it is.

On my Z71 with the 3" readylift I cranked the wheel all the way to the left, pulled back on the fender liner, and was able to install it.
With other trims it may be trickier if the fender liner sits lower than the Z71.
And the 3" lift gives more space.
But with all that said I think even stock non-Z71 it's probably doable this way, maybe just have to remove a couple of the fender liner screws.

So I got the Range disabler yesterday and just put it in this afternoon. It was pretty straight forward. Put the Yukon on the highest suspension setting and turned the steering wheel all the way to the left. It provided just enough clearance for me to get back there without taking the tire off (I was really hoping not to have to do all that). Disconnected the negative battery terminal, and then removed 7 torque screws to open up the liner in the wheel well. I was able to pull it back just far enough to access the ECM connectors. It took some finger gymnastics, but got the bottom one off, the Range disabler connected, and the GMC connector locked back on.

Just got back from a test drive and it works beautifully. I have the GMC performance exhaust on the 6.2L, so it's really easy to tell that all 8 cylinders are firing all the time. It's overall very smooth. On the freeway, there's no shake on light throttle. It fixed a lot of annoying issues that I suppose are a result of the DFM activation. It feels like DFM is disabled on my rig at all times, but I really am not nuanced enough to know for sure. I do know that it doesn't shudder/jitter at traffic lights anymore.

 

[DontTaseMeBro]

I forget if this was answered, but is there any way to know if DFM is working? I can’t tell on my at all. I don’t hear any sound and don’t feel anything. So either it’s that good or maybe it came without when my engine was replaced last year. I’m sure it’s just that good but still wanna know.

 

[K5-Z71]

I forget if this was answered, but is there any way to know if DFM is working? I can’t tell on my at all. I don’t hear any sound and don’t feel anything. So either it’s that good or maybe it came without when my engine was replaced last year. I’m sure it’s just that good but still wanna know.

When I got this truck at 7,500 miles there were no perceivable changes when DFM activated, after locking out the exhaust resonator I could hardly hear it working. Now at 43,000 miles I absolutely can hear and feel the DFM activations, this product fixed it!

I simply removed the lowest three wheel well liner fasteners then laid on my back from the front of the vehicle to do the work. No turning of the wheel or jacking of suspension required.

I’m not overly paranoid about lifter failure but reducing drivetrain vibration is easily worth the price.

 

[BacDoc]

It’s just not clear why it is needed. On the 5th generation GM cars, there are no problems with pushers. And in the problems with the 4th generation pushers, no one has proven that the DFM system is to blame. If you turn it off, then by completely reworking the engine, removing it completely, and not an incomprehensible block in the OBD. If you already want to, you can drive in the “Trailer” mode; DFM/AFM does not work in it.

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.

 

[nick14226]

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.

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…

 

[BacDoc]

I’m a beta tester, 100% worth it if you’re like me and the DFM causes noticeable lugging/vibration when maintaining speed or slight throttle tip in. I absolutely hate driveability with AFM/DFM on the v8’s. Wifes AFM on her v6 blazer on the other hand, don’t even notice it.

Install was very easy, not as easy as an OBD plug in, but super simple.

What year is your truck?

 

[nick14226]

What year is your truck?

2022 Tahoe z71 5.3

 

[K5-Z71]

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]

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]

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]

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]

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]

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]

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]

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]

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

 

[nick14226]

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