Carbyte (DFM disabler for 2024) limited giveaway
- Thread starter Carbyte
- Start date
'24 Sierra AT4 - I have not seen the mpg screen go to "99" other than a couple times. Both of these occurrences were shortly after installing the device.
From Ontario, Oregon to The Dalles 299mi 75mph on cruise other than slowing on curves and traffic in Sport mode..... 19.1 mph average
The Dalles back to Ontario same driving speeds but in Highway mode..... 18.4 mph average
The Dalles back to Ontario same driving speeds but in Highway mode..... 18.4 mph average
- Thread Starter
- #79
“99 mpg as ‘DFM enabled’ indicator”
My last response about using instantaneous fuel consumption value as an indicator of DFM status created some confusion. Sorry about that.
TL;DR - The meaning of “99 mpg” depends on the model year and driving conditions, so it is not a 100% reliable indicator of DFM status. If you are interested in the nuances and technical details, read on.
Late 2022+ Models
In late 2022, GM introduced a new management system into their trucks and SUVs that significantly differs from the earlier implementations. The new system prevents the complete deactivation of DFM until the vehicle speed exceeds 40 mph at least once. Until this happens, you may occasionally see “99 mpg” during deceleration. However, once the 40 mph speed threshold is reached, Carbyte is able to deactivate DFM for the remainder of the drive cycle and the instantaneous fuel economy value becomes a reliable indicator of the DFM system status (99 mpg = DFM active).
To be clear: the vehicle speed needs to reach 40 mph just once for Carbyte to fully deactivate the DFM system. It then remains deactivated at any speed (0+ mph) for the remainder of the drive (until the engine is turned off).
Early 2022 and Older Models
On older vehicles, Carbyte is able to deactivate AFM immediately after engine start. Unfortunately, on these vehicles instantaneous fuel economy value is not a reliable AFM status indicator. Carbyte disables AFM but does not disable fuel cutoff on deceleration, which shows up as “99 mpg”. The good news is, many of these vehicles display the AFM status on the instrument panel (“V4/V8”).
Other Ways to Tell If AFM/DFM Is Active
On some models, it’s easy to tell when AFM/DFM activates based on the characteristic change in engine sound and vibration. We are looking into the possibility of adding an AFM/DFM status indicator to the Carbyte app.
My last response about using instantaneous fuel consumption value as an indicator of DFM status created some confusion. Sorry about that.
TL;DR - The meaning of “99 mpg” depends on the model year and driving conditions, so it is not a 100% reliable indicator of DFM status. If you are interested in the nuances and technical details, read on.
Late 2022+ Models
In late 2022, GM introduced a new management system into their trucks and SUVs that significantly differs from the earlier implementations. The new system prevents the complete deactivation of DFM until the vehicle speed exceeds 40 mph at least once. Until this happens, you may occasionally see “99 mpg” during deceleration. However, once the 40 mph speed threshold is reached, Carbyte is able to deactivate DFM for the remainder of the drive cycle and the instantaneous fuel economy value becomes a reliable indicator of the DFM system status (99 mpg = DFM active).
To be clear: the vehicle speed needs to reach 40 mph just once for Carbyte to fully deactivate the DFM system. It then remains deactivated at any speed (0+ mph) for the remainder of the drive (until the engine is turned off).
Early 2022 and Older Models
On older vehicles, Carbyte is able to deactivate AFM immediately after engine start. Unfortunately, on these vehicles instantaneous fuel economy value is not a reliable AFM status indicator. Carbyte disables AFM but does not disable fuel cutoff on deceleration, which shows up as “99 mpg”. The good news is, many of these vehicles display the AFM status on the instrument panel (“V4/V8”).
Other Ways to Tell If AFM/DFM Is Active
On some models, it’s easy to tell when AFM/DFM activates based on the characteristic change in engine sound and vibration. We are looking into the possibility of adding an AFM/DFM status indicator to the Carbyte app.
Johnv76
Well-known member
- Joined
- May 20, 2024
- Messages
- 755
- Reaction score
- 552
- Location
- Austintown, Ohio
- Military
- US Army Combat Veteran
Awesome explanation.
Thank you for the clarification. For the late 2022+ models - are there going to be any improvements released in the future to disable DFM 100%?
I know this is an AT4 forum, but there is no really good Sierra 1500 forum. Before I bought my new truck, 2024 GMC Sierra 1500 Denali 6.2L Carbon Pro, I was concerned about the cylinder disabling because it has ALWAYS been a failure point in just about every brand of vehicle it has been used on.
I was glad to see the Carbyte product and had one ordered two days after I bought the truck on 10/27/24. I've been so busy adding products that I haven't had time to really see what it does. I only have 300 miles on the truck, but I know the Auto Stop is turned off and I run the DIC with the MPG showing. I've never seen the 99MPG on deceleration. I've been watching it closely to see what kind of mileage I'm getting compared to my Raptor.
I don't know what the truck is supposed to do or if it's normal, but in NORMAL mode, on cold startups, the Active Exhaust is on, but then quiets down.
Since new, I've installed, WeatherTech mats, bed pad, 2" leveling kit, wheel well liners, BakFlip MX4 tonneau cover, dash cam and wiring, trailer harness wiring for towing the truck behind my motorhome, base plates for towing the truck and a braking system. I'm getting too old for this stuff.
I had it aligned today, after I installed the leveling kit. I guess I can now start paying attention to what the Carbyte does. I've only been driving around town and seeing about 12-13 mpg.
I was glad to see the Carbyte product and had one ordered two days after I bought the truck on 10/27/24. I've been so busy adding products that I haven't had time to really see what it does. I only have 300 miles on the truck, but I know the Auto Stop is turned off and I run the DIC with the MPG showing. I've never seen the 99MPG on deceleration. I've been watching it closely to see what kind of mileage I'm getting compared to my Raptor.
I don't know what the truck is supposed to do or if it's normal, but in NORMAL mode, on cold startups, the Active Exhaust is on, but then quiets down.
Since new, I've installed, WeatherTech mats, bed pad, 2" leveling kit, wheel well liners, BakFlip MX4 tonneau cover, dash cam and wiring, trailer harness wiring for towing the truck behind my motorhome, base plates for towing the truck and a braking system. I'm getting too old for this stuff.
I had it aligned today, after I installed the leveling kit. I guess I can now start paying attention to what the Carbyte does. I've only been driving around town and seeing about 12-13 mpg.- Thread Starter
- #83
Carbyte disables DFM 100% after the vehicle reaches the 40 mph threshold and until the engine is turned off. Unfortunately, if the speed never reaches 40 mph Carbyte is unable to get a complete lock on the DFM. As far as we can tell, there is no way to overcome this limitation without modifying the ECU software.
Thanks....today I was checking/working on the procedure for putting the truck into Neutral Tow for towing behind my motorhome. I had never linked the Carbyte to phone. I had to remove and reinsert it and it linked up. It showed Auto Stop was off and DFM was disabled. Everything is working well.
After the 19 and 18 it should have been mpg not mph
Hello, I’ve recently purchased this unit and plugged it in a week ago and it definitely disables the AutoStop, however I am still getting the zero cylinder issue. Do I need to maintain a 40+ mph speed for a specific amount of time for it to grab onto the DFM? Also, are the lights on this unit supposed to always be on/blinking even when the truck is parked in my driveway? Thank you!
Note: I have a 24 1500 SLT 5.3 Aftermarket cat-back exhaust so very noticeable.
- Thread Starter
- #87
Carbyte Lights Staying On
The lights switch off when Carbyte goes into sleep mode - around 10 minutes after the engine is switched off. The lights will come back on when the vehicle wakes up, and the newer trucks wake up when you walk up to them while carrying the key.
40mph requirement
Under normal circumstances it only requires a few seconds of traveling at 40mph for the truck to perform its systems test and for Carbyte to get a lock on the DFM. However, under certain conditions the systems test might not start until the vehicle is traveling at a higher speed (when using larger tires for example).
To make sure the systems test is performed fully, bring the truck to 45+ mph on a flat, or slightly uphill ground, then let off the throttle all the way for 3-5 seconds, then bring it back up to 45mph or higher.
If, after trying this, you’re still experiencing issues, please contact us via support. This way we’ll be able to get data from your Carbyte to see exactly what’s happening.
Deano's AT4
New member
Just an FYI, If your truck has a ELO GPS tracker " Not sure on other tracking devices" the unit will not work. My ELO was dealer installed. I’m considering just disconnecting it as I think the benefit of disabling the DFM outweighs the tracker . I also may reach out to Range technology’s to see if their unit will work with a tracking device installed.
Last edited:
ELO??? Electric Light Orchestra??? Wow a blast from the past.
Seriously though, I'd be all over un-installing that tracker.
Ctmedic
Member
- Joined
- Sep 1, 2024
- Messages
- 40
- Reaction score
- 21
- Location
- Connecticut
- First Responder
- Paramedic & Firefighter
Do you have to connect this in the app every time ?
