Hyundai Santa Fe (TM): Engine Control System / Variable Force Solenoid (VFS). Description and operation

CVVT (Continuous Variable Valve Timing) system advances or retards the valve opening and closing timing of the intake or the exhaust valve in accordance with the ECM control, calculated by the engine speed and the load. The CVVT control causes a valve over-lap or under-lap between the intake valve and the exhaust valve. This improves fuel efficiency, reduces exhaust gases (NOx, HC) and enhances the engine performance, thanks to reduced pumping loss, internal EGR (Exhaust Gas Recirculation) release, improved combustion stability, and increased volumetric efficiency.The system consists of the CVVT Oil Control Valve (OCV), which receives the ECM PWM (Pulse With Modulation) control signal to change the path of the engine oil to supply to or discharge from the cam phaser, the CVVT Oil Temperature Sensor (OTS), which measures the temperatures of the engine oil, and the cam phaser, which varies the cam phasing by using the hydraulic force of the engine oil.The oil delivered from the CVVT oil control valve varies the phase angle of the cam, by rotating the rotor connected to the camshaft of the cam phaser and causing the camshaft to rotate in the direction of its engine running rotation (intake advanced / exhaust retarded) or the opposite direction (intake retarded/ exhaust advanced).