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 timing misalignment while no active faults is present and fully warmed up engine oil at idle.
If the timing is misaligned ECM determines that a fault exists and a DTC is stored.
Item
Detecting Condition
Possible Cause
DTC Strategy
Determines if CAM target is aligned correctly to crank
loosened CKPS
Timing Misalignment
Enable Conditions
No active faults
Fully warmed up at idle
Threshold value
Case 1
1 tooth misalignment at 80 ?(176 ?)
< Oil Temperature < 90 ?(194?)
Case 2
2 teeth misalignment at Lower than 80 ?(176 ?) or Higher than 90 ?(194?)
Diagnosis Time
Continuous (Within 1min.)
MIL On Condition
3 Driving Cycles
Engine Oil Temperature
Misalignment
80 ?(176 ?) < ENgine Oil Temperature < 90 ?(194?)
1 tooth
Less than 80 ?(176 ?) or Higher than 90 ?(194?)
2 teeth
Fig.1) Normal waveform of CKPS & CMPS at idle.
This example shows a typical Crankshaft Position Sensor (CKPS) and Camshaft Position Sensor (CMPS) waveform at idle. If the 17th signal of the CKPS after missing tooth is aligned with the high signal of the CMPS at idle, ECM recognizes that Synchronization between CKPS and CMPS is completed.