DFM disabler released

JasonHTX · Sep 19, 2024

nick14226 said:
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 · Sep 19, 2024

JasonHTX said:
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 · Sep 19, 2024

nick14226 said:
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 · Sep 27, 2024

nick14226 said:
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 · Sep 27, 2024

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 · Sep 28, 2024

DontTaseMeBro said:
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 · Sep 28, 2024

Vladimir2306 said:
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 · 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.

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 · Sep 28, 2024

nick14226 said:
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 · Sep 28, 2024

BacDoc said:
What year is your truck?

2022 Tahoe z71 5.3

DFM disabler released

JasonHTX

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