2001 Toyota Corolla TRYING TO TROUBLESHOOT VVT PROBLEM

AFTER A 1500 MILE ROAD TRIP MY CORROLLA STARTED MAKING A VALVE KNOCK NOISE COMING FROM UNDER THE VALVE COVER ON THE LEFT SIDE, FACING THE CAR, IT ALSO HAD A CHECK ENGINE LIGHT WITH A P1349 CODE WHICH I CHECKED AND FOUND WAS A VVT SYSTEM CODE, I PULLED AND CHECKED THE VVT SOLENIOD OR OIL CONTROL SOLENIOD, AND THE PLUNGER IS MOVING FREELY WITH NO BINDING, AND OPERATED ELECTRICY WHEN BENCH TESTED, AFTER PUTTING IT TOGETHER, I STARTED THE CAR WITH THE VVT DISCONECTED AND IT RAN FINE WITH NO KNOCKING, OBVIOSLY WITH OUT THE BENIFIT OF VVT. WITH THE VVT HOOKED BACK UP THE NOISE IS INTERMITTENT, I AM THINKING IT IS SOMTHING OTHER THAN THE SOLENOID AS IT IS OPERATING BUT NOT AT THE RIGHT TIME. WHAT OTHER COMPONENTS ARE IN THE VVT SYSTEM THAT MIGHT BE CAUSING THIS?