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 overall 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.
Item
Detecting Condition
Possible Cause
DTC Strategy
Determines if oil control valve is stuck
Oil Pressure Loss
OCV seizure
Enable Conditions
Valve cleaning not in progress
CAM signal is normally generating
Threshold value
Case 1
Cam Actual Position > 50 CAD and Difference between CAM Actual Position and Desire Position > 20 CAD
Case 2
Cam Actual Position < 5 CAD and Difference between CAM Actual Position and Desire Position > 20 CAD
Diagnosis Time
Continuous (Within 1min.)
MIL On Condition
2 Driving Cycles
OCV
Specification
Coil Resistance (?)
6.7 ~ 7.7 (20?)
Fig 1) Normal waveform of OCV at idle.
Fig 2) Normal waveform of OCV at acceleration. (3500rpm)
Fig 3) Normal data of IN-CVVT at idle.
Fig 4) Normal data of EX-CVVT at acceleration.
Fig 5) Normal graph of EX-CVVT at acceleration.