Which GM Engines Don't Have The AFM System?

In an effort to help meet more restrictive emissions standards, GM launched a technology in 2005 that deactivates engine cylinders during undemanding driving scenarios. Known by both Displacement on Demand (DOD) and Active Fuel Management (AFM), this system would automatically shut down half of the engines cylinders, reducing the fuel used and limiting emissions at the same time. Considering this technology was implemented in some of the automakers largest engines, including GMs ECOTEC3 5.3L V8, not all drivers were thrilled. Lack of enthusiasm for the technology is evident, with many products available that claim to be able to disable AFM and how-to instructional walkthroughs guiding drivers on how to disengage it.

If you want to avoid this technology, obviously owning a GM engine prior to 2005 won't feature it. But what about after 2005? The LM2 Duramax 3.0L turbo-diesel, the L8T 6.6L V8, and the LS3 have neither AFM nor the latest version, called DFM (Dynamic Fuel Management). In addition, some 5.3L V8s from 2021 and 2022 don't include either fuel-saving system due to semi-conductor shortages manufacturers were dealing with during that time. You'll need to be careful, though, when comparing options like the LS3 vs L99 engine for the Camaro, in which the latter includes AFM, negatively affecting performance.

If you're not sure whether a particular GM vehicle has the AFM system in its engine, there are a few methods to identify it. First, you can check the owner's manual for the vehicle, which can often be downloaded online. Listed in the contents should be a section about the technology if it's present. However, if you run into a case where the manual states, "If equipped" regarding AFM, what then?

GM has equipped most of its engines with this technology, and the company hasn't been shy about advertising it. Therefore, you can also find mention of AFM in places like the sticker on the vehicle's window. This should offer you more details about the engine in the vehicle, with highlights regarding its improved efficiency if AFM is present. We noted a few years ago that, in addition to the Corvette C7 increasing its weight over the C6 by 90 pounds, it also included the AFM technology, which could be off-putting for enthusiasts.

When the technology was first touted, GM made promises that drivers didn't end up experiencing in their day-to-day travels. For example, according to Newparts.com, "GM claimed that the feature improved fuel efficiency by up to 12%, but owners have reported that the figure is closer to 5% in real-world conditions." If this were the only issue reported about AFM, it would still seem like a net positive addition to the engine, but unfortunately, the troubles extend beyond this.

AFM introduced a much more intricate routine of operations to the engine that required sophisticated software. Per MotorTrend.com, "These systems greatly increased the complexity of the engine management systems, and they also hurt the legendary durability these engines were famous for." Many owners of GM vehicles reported problems, including excessive oil consumption and component failures due to the AFM system. There are even reports of the combustion chambers becoming clogged with debris, causing a drop in fuel economy, which defeats the whole purpose of the fuel-saving technology. Considering these reports, it's not a surprise that some drivers look for GM engines without this technology.