is after the intake valve is lifted i e opened by the cam and when the cam is no longer holding the intake valve open the hydraulic fluid may hold the intake valve open for a desired period the desired period may change depending on the desired performance of the engine a controller 19 may be provided for controlling operation of the internal combustion engine the controller 19 may be operatively connected to the egr valve 13 the wastegate 15 and the intake valve closing mechanism of each cylinder 11 the controller 19 may also be operatively connected to one or more sensors 20 which may provide the controller 19 with indications of one or more engine conditions or other data from which the loading of the internal combustion engine can be determined the sensors 20 may include sensors detecting engine speed engine torque or detecting the work state of a vehicle in which the internal combustion engine is incorporated for example sensors detecting heavy digging hill climbing or fast digging may be utilised the operation of the intake valve may be switched from the first operating profile 30 to the second operating profile 31 instantaneously by u2018 instantaneously u2019 is meant that the switching of operation from the first operating profile to the second operating profile is not phased gradually over many engine cycles rather switching may take place between one engine cycle and the next engine cycle for example within one revolution of a cam shaft of.