A valve actuator assembly for an engine includes a movable engine valve and a
movable
spool valve. The valve actuator assembly also includes a driving channel interconnecting
the spool valve and the engine valve and a feedback channel interconnecting the
spool valve and the engine valve. The valve actuator assembly includes an actuator
operatively cooperating with the spool valve to position the spool valve to prevent
and allow fluid flow in and out of the driving channel to position the engine valve.
The valve actuator assembly further includes an on/off valve in fluid communication
with the feedback channel to enable and disable the feedback channel to control
motion of the spool valve.