The CVVT (Continuously Variable Valve Timing) system is installed to the chain sprocket of the intake camshaft. This system controls the intake camshaft to provide the optimal valve timing for every driving condition. The ECM controls the Oil Control Valve(OCV), based on the signals output from mass air flow, throttle position and engine coolant temperature. The CVVT controller regulates the intake camshaft angle using oil pressure through the OCV. As result, the relative position between the camshaft and the crankshaft becomes optimal, and the engine torque improves, fuel economy improves, exhaust emissions decrease under over all driving conditions.

ECM monitors OCV stuck while cam sinal is normally generating and Valve cleaning is not in progress .

If the CAM Acutal Position is too high or low and Difference between Cam Actual Positionand Desire Position is higher than 20° ECM determines that a fault exists and a DTC is stored.

Fig.1) Normal data of IN-CVVT at idle.

Fig.2) Normal data of IN-CVVT at acceleration with load.

Fig.3) Normal graph of IN-CVVT at acceleration with load.

Fig.4) Normal waveform of OCV at idle.

Fig.5) Normal waveform of OCV at idle.

The oil control valve is commanded by a pulse-with-modulated signal from the engine control unit. A duty cycle of zero commands the cam phaser to its default position. A duty cycle of 100% commands the cam phaser to its maximum phased position. When the phaser must be controlled to an intermediate position, the duty ccle is maintained in the region of the 'hold position'. This is a medium duty cycle, usually between 35% and 65%, depending on temperature and voltage conditions.