P0021

COMPONENT LOCATION





GENERAL DESCRIPTION

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.

DTC DESCRIPTION

This diagnostic monitors the phasing response rate and determines whether the response rate is fast enough. A state machine is used to capture the response rate. The measured results are then compared to an allowable threshold. The threshold is a function of the oil temperature and the requested desired rate. Test of the phaser response rate requires an engine speed or engine load change.

PCM detects CAM phasing average rate while cam offset is available.If the CAM phasing rate is failure in 12 times out of 15 CAM phasing test PCM determines that a fault exists and a DTC is stored.

DTC DETECTING CONDITION





SIGNAL WAVEFORM AND DATA





SCHEMATIC DIAGRAM





MONITOR DTC STATUS

1. Connect scantool to Data Link Connector(DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) to check DTC's information from the DTCs menu
4. Read "DTC Status" parameter.




5. Is parameter displayed "Present fault"?
YES
> Substitute with a known - good Thermostat and check for proper operation.
If the problem is corrected, Go to "Verification of Vehicle Repair" procedure.
NO
> Fault is intermittent, go to "Verification of vehicle Repair" procedure.

SYSTEM INSPECTION

1. Visual Inspection
(1) Check oil level is O.K.
(2) Check oil level is contaminated
(3) Check that any oil leakage or blockage is occurred on the parts related to CVVT.
(4) Has a problem been found ?
YES
> Repair or replace as necessary and then, go to " Verification of Vehicle Repair" procedure.
NO
> Go to "Component Inspection" procedure

COMPONENT INSPECTION

1. Check OCV
(1) Connect scantool and IG "ON"
(2) Select "OCV" on the Actuation Test
(3) Activates "OCV" by pressing "STRT(F1)" key
(should hear a faint click from Oil Control solenoid Valve)
(4) Repeat this procedure 4 or 5 times to ensure intake valve control solenoid reliability




(5) Has a problem been found ?
YES
> Substitute with a known - good CVVT and check for proper operation.
If the problem is corrected, replace CVVT and go to "Verification of Vehicle Repair" procedure.
NO
> Substitute with a known - good OCV and check for proper operation.
If the problem is corrected, replace OCV and go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR

After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all rediness test have been verified as " Complete "
5. Are any DTCs present ?
YES
> Go to the applicable troubleshoooting procedure.
NO
> System is performing to specification at this time.