The Continuously Variable Valve Timing (CVVT) system is installed on the chain sprocket of the intake camshaft. This system controls the intake camshaft to provide the optimal valve timing for all driving conditions. The PCM controls the Oil Control Valve (OCV), based on the signal outputs from Manifold Absolute Pressure (MAP), throttle position and engine coolant temperature. The PCM regulates the intake camshaft angle using oil pressure through the OCV. As a result, the relative position between the camshaft and the crankshaft becomes optimal. The engine torque improves, fuel economy improves, and exhaust emissions decrease under overall driving conditions.