Posted on 6/11/2025
Active Fuel Management (AFM)—also known as Cylinder Deactivation—is GM’s variable-displacement engine technology. It's designed to improve fuel economy by allowing V6 and V8 engines to deactivate cylinders under light-load conditions, such as steady highway driving. When deactivated, these cylinders are closed off and filled with trapped air, effectively turning them into air springs. This reduces energy loss through pumping, helping the engine run more efficiently while maintaining a smooth driving experience. 👨🔧 How AFM Works 🔧 Hydraulic Lifter Control AFM uses a combination of solenoids and hydraulically-actuated lifters, located in the engine valley, to disable specific intake and exhaust valves. These lifters, supplied by Eaton and Delphi, temporarily prevent certain cylinders from firing, allowing the engine to operate in a leaner mode when full power isn't ... read more