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 CAM phaser error while CMP signal is normally generating and vehicle is driving in 2000 ~ 3000rpm.
If the CAM phaser does not move although ECM commands OCV duty cycle ECM determines that a faultexists and a DTC is stored.
Item | Detecting Condition | Possible Cause | |
DTC Strategy |
•
Determines if the phaser is stuck or has steady-state error | 1. Engine Oil 2. OCV stuck 3. CVVT stuck | |
Enable Conditions |
•
CAM signal is normally generating
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Vehicle is on driving (2000 ~ 3000RPM) for 5 minutes | ||
Threshold value | Case 1 |
•
5 CAD < Cam Actual Position < 50 CAD
•
Duty Cycle > 90% or Duty Cycle < 10% | |
Case 2 |
•
Cam Position error > 15 CAD (Difference between Actual Postion and Desire Position is more than 15°)
•
Timing Counter > 80 | ||
Diagnosis Time |
•
Continuous (within 5min.) | ||
MIL On Condition |
•
2 Driving Cycles | ||
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 CKPS & IN-CMPS at idle.
Fig.5) Normal waveform of CKPS & IN-CMPS at acceleration with load.
This example shows a typical Crankshaft Position Sensor (CKPS) and Camshaft Position Sensor (CMPS) waveform at idle.(Fig.4) If the 17th signal of the CKPS after missing tooth is aligned with the high signal of the CMPS at idle, PCM recognizes that Synchronization between CKPS and CMPS is completed. Under acceleracting condition, the number of teeth between missing tooth and tooth aligned with edge of the CMPS high signal is decreased from idle condition.(Fig.5)
