When did GM switch from AFM to DFM?
GM began switching from Active Fuel Management (AFM) to Dynamic Fuel Management (DFM) with the 2019 model year, and by the early 2020s the switch had largely taken hold across its gasoline V8 lineup. This article outlines the timeline, the engines affected, and what it means for owners today.
What AFM and DFM are
AFM, or Active Fuel Management, is GM’s cylinder deactivation technology that can shut down half of a V8’s cylinders to save fuel under light-load conditions. DFM, or Dynamic Fuel Management, is the evolved system designed to offer more flexible cylinder deactivation patterns and smoother transitions between modes, aiming to improve efficiency without sacrificing performance.
Before diving into the timeline, here is a quick overview of how the two systems differ in practice:
- AFM typically deactivates a fixed portion of cylinders (commonly half) during light-load driving.
- DFM broadens deactivation options and aims for finer control, improving efficiency across a wider range of driving situations.
- Both systems are designed to operate transparently to the driver, but DFM is marketed as offering better real-world fuel economy and smoother operation in more scenarios.
In summary, DFM represents GM’s effort to make cylinder deactivation more adaptable to varying driving conditions while maintaining performance when needed.
Timeline: When GM switched
The following milestones outline the spread of Dynamic Fuel Management across GM’s gasoline lineup and the phasing out of AFM on new vehicles.
- 2019 model year: GM introduces Dynamic Fuel Management on core V8 engines in pickups and large SUVs (notably the 5.3L and 6.2L EcoTec3 engines in Silverado/Sierra and related models), marking the formal replacement of AFM on new vehicles.
- 2020 model year: DFM becomes more widely standard across additional trims and related platforms, signaling a broader shift away from AFM on fresh GM gasoline offerings.
- 2021–2023 model years: DFM rollout continues across the GM light-truck lineup, with AFM largely absent from new models in favor of Dynamic Fuel Management.
Conclusion for this timeline: The switch from AFM to DFM began with the 2019 model year and accelerated through 2020 and beyond, with most new GM gasoline-powered trucks and large SUVs adopting DFM by the early 2020s.
Engines and models affected
GM’s DFM rollout targeted its flagship gasoline engines used in pickups and large SUVs. Here are the broad categories that saw the shift.
- Chevrolet Silverado and GMC Sierra: Core V8s such as the 5.3L EcoTec3 and the 6.2L EcoTec3 moved to DFM starting with the 2019 model year.
- Chevrolet Tahoe/Suburban and GMC Yukon/Yukon XL: Similar adoption for the large V8s in these full-size SUVs began around 2019–2020.
- Other GM pickups and SUVs with EcoTec3 V8s: The DFM transition extended to additional trims and configurations in the following years, as GM aligned its lineup.
In practice, the early emphasis was on the high-volume, high-visibility platforms (Silverado/Sierra and their large SUV siblings), with broader coverage expanding over the next couple of years.
What owners should know
For current owners and buyers, the shift to DFM carries several practical implications. Here are key points to consider.
- Fuel economy and drive feel: DFM aims to deliver better real-world fuel economy across a wider range of driving scenarios while preserving strong acceleration when demanded.
- Reliability history with AFM: Early AFM implementations faced concerns about lifter wear and related issues in some engines; GM updated hardware and software in later years to address reliability questions. In most cases, owners of newer DFM-equipped vehicles should not experience these legacy issues.
- Maintenance and service: If you own an older GM vehicle originally equipped with AFM, some owners opt to disable AFM via dealer service or aftermarket tuning. This is a decision to discuss with a qualified technician, as disabling cylinder deactivation can affect warranty coverage and emissions compliance in some regions.
Concluding note: For most buyers, the transition to DFM means improved efficiency routines on GM’s gasoline engines without a noticeable drop in performance. However, if you own a legacy AFM-equipped vehicle, consult with a dealer about options and potential long-term reliability considerations.
Summary
GM’s transition from AFM to DFM unfolded primarily with the 2019 model year, followed by a broader rollout through 2020 and into the early 2020s. The shift targeted core V8 gasoline engines in pickups and large SUVs, delivering more flexible cylinder deactivation and improved real-world efficiency. While AFM remains a topic for legacy vehicles, the industry trend under GM has been to standardize Dynamic Fuel Management across its new gasoline offerings. For owners, this means a newer generation of GM trucks and SUVs that balance performance with enhanced fuel economy, along with considerations for legacy AFM-equipped vehicles and the options available to address them.
What year do GM trucks have Active Fuel Management?
GM started using Active Fuel Management (AFM) in trucks with the 2005 model year, first introducing it on certain 5.3L V8 engines in SUVs like the GMC Envoy and Chevrolet TrailBlazer. The system was later extended to other trucks and V8 engines, including some 6.0L engines in 2005, though it was not a feature on all trucks at that time.
- Initial introduction: AFM was first commercially available on some 2005 models, specifically the optional Vortec 5300 V8 in the GMC Envoy XL, Envoy XUV, and Chevrolet TrailBlazer EXT SUVs, notes Wikipedia.
- Extension to trucks: While the initial rollout was in SUVs, the technology was also extended to some truck models with the same 5.3L and 6.0L engines starting around the same time.
- Continued use: The system was in use on a variety of V8 engines in trucks and SUVs in the following years.
Is DFM better than AFM?
Dynamic Fuel Management (DFM) is generally considered better than Active Fuel Management (AFM) for efficiency, as it can deactivate any number of cylinders in various combinations, leading to greater fuel savings. However, DFM is a more complex system with a higher failure rate at lower mileages due to the increased number of components, particularly the lifters, though older AFM systems are prone to failure at higher mileages.
Dynamic Fuel Management (DFM)
- More efficient: DFM can deactivate a variable number of cylinders (from 1 to 7 on an 8-cylinder engine) in numerous combinations, optimizing fuel efficiency more effectively than AFM.
- Seamless transitions: It can change which cylinders are active on the fly with 17 different firing combinations, resulting in smoother operation and less noticeable transitions.
- More complex: The increased complexity means DFM engines are more susceptible to failures, especially related to the lifters, at lower mileage levels compared to AFM engines.
Active Fuel Management (AFM)
- Less efficient: AFM deactivates only four specific cylinders (in a fixed pattern, such as the four on one side of the engine).
- Simpler system: It has fewer components and a simpler operation compared to DFM.
- Prone to failure at higher mileage: While DFM has more issues at lower mileages, AFM systems are known for failure, particularly collapsed lifters, that tend to occur at higher mileage levels due to their age.
Which is better for you?
- For performance and efficiency: DFM is technically superior because it offers better fuel economy and smoother operation, as explained by Future Chevrolet.
- For long-term reliability: AFM may be more reliable in the long run, as the DFM system is still relatively new and has a higher initial failure rate, according to Boost AFM Disabler.
- If considering an AFM/DFM disabler: A disabler can be used to prevent cylinder deactivation in both systems, which might help reduce some issues but doesn't prevent all problems, notes Reddit users.
What year did GM stop using DFM?
Between March of 2021 and the end of the 2022 model year, GM removed DFM (and, by extension, auto stop-start) from select GM trucks and SUVs equipped with the naturally aspirated 5.3L V8 L84 gasoline engine.
Does DFM cause lifter failure?
The two most common problems with AFM & DFM are lifter failure and excessive oil consumption. Lifter failure is extremely common once vehicles start reaching the 150,000 mile mark.
