Patent ID: 7178491

Claim:
A method of controlling a variable valve actuation system for an engine, comprising: moving an engine valve between a first position where the engine valve blocks a flow of fluid and a second position where the engine valve allows a flow of fluid; providing fluid to a chamber of a valve actuator adapted to operatively engage the engine valve; sensing a parameter indicative of a viscosity of the fluid provided to the chamber of the valve actuator; trapping fluid within the chamber of the valve actuator to prevent the engine valve from moving to the first position; determining a response time of the valve actuator as a function of the sensed parameter indicative of viscosity, the response time indicating the time required to release the fluid from the chamber of the valve actuator to allow the engine valve to move to the first position; determining a desired valve actuation period; and releasing the fluid trapped in the chamber of the valve actuator to thereby release the engine valve at a time based on the response time of the valve actuator such that the engine valve moves to the first position at the end of the desired valve actuation period.