N52 engines in 328i and 330i models are equipped with 3-stage variable intake runners in a system known as DISA. Valves in the intake manifold are driven by DISA electric motors and gear mechanisms. DISA actuators are driven by pulse widthmodulated signals from the engine control module (ECM). Each valve has only two possible positions: Open or closed. Switched-length intake manifold runners help achieve a high torque over the entire engine speed range using two DISA valves and an overflow pipe in the intake. Stage 1: Idle and low engine speed range. Both DISA valves closed. In this position, a relatively large air mass is made available to cylinders. Stage 2: Medium engine speed range. DISA valve 2 open. Air flow produces pressure peaks at closing intake valves. This resonates to next cylinder in firing order, thus improving charge of next cylinder. Stage 3: High engine speed range. Both DISA valves open. Pressure peaks ahead of closing intake valves are also utilized in this position. Intake air mass is now routed via resonance, overflow and manifold runners.