Variable Cylinder Management

Variable Cylinder Management (VCM) is Honda's term for its variable displacement technology, which saves fuel by deactivating the rear bank of 3 cylinders during specific driving conditions—for example, highway driving. It was first introduced in the 2005 Honda Odyssey minivan. The second version of VCM (VCM-2) took this a step further, allowing the engine to go from 6 cylinders, down to 4 or 3 during cruising and deceleration. This version had an "ECO" indicator light on the dashboard. The most recent version of VCM (VCM-3) reverted to the previous 3- and 6-cylinder operation.

Unlike the pushrod systems used by DaimlerChrysler's Multi-Displacement System and General Motors' Active Fuel Management, Honda's VCM uses overhead cams. A solenoid unlocks the cam followers on one bank from their respective rockers, so the cam follower floats freely while the valve springs keep the valves closed. The system operates through controlling the flow of hydraulic engine oil pressure to locking mechanisms in the cam followers. The engine's drive by wire throttle allows the engine management computer to smooth out the engine's power delivery, making the system nearly imperceptible on some vehicles. When the VCM system disables cylinders, an "ECO" indicator lights on the dashboard, Active Noise Cancellation (ANC) pumps an opposite-phase sound through the audio speakers to reduce cabin noise, and Active Control Engine Mount (ACM) systems reduce vibration.