A method of phasing the opening and closing of internal combustion engine intake and exhaust valves relative to the rotation of the crankshaft is based upon changes in engine speed, engine load and ambient relative humidity. During certain conditions of higher humidity, in order to maintain good combustion stability and thus overall engine operation, it is necessary to reduce intake and exhaust valve overlap by adjusting the phase of the intake and exhaust camshafts. This is achieved by utilizing a set of cam position reference values and constraints based upon engine speed, engine load and humidity that are contained in lookup tables that adjust and limit cam position and valve overlap. Generally speaking, in order to maintain optimum engine performance, intake and exhaust valve overlap is reduced with higher ambient humidity and vice versa.

A method for controlling continuously variable valve timing (CVVT), may include determining whether a CVVT control is started, detecting a position of a cam and a position of a crankshaft when the CVVT control is started, determining whether the cam is positioned at a locking position based on the positions of the cam and crankshaft, determining whether the cam is controlled to be positioned from the locking position to an advancing position or a holding position, when the cam is positioned at the locking position, and when the cam is controlled to be positioned from the locking position to the advancing position or the holding position and when a condition for performing the CVVT control is satisfied, determining whether a cam torque is negative and performing predetermined CVVT control after waiting a predetermined time when the cam torque is negative.

A cylinder head assembly for an internal combustion engine has a housing (12) in which a plurality of elements (18, 44) are arranged. An optical duct (24) is formed in the housing (12) and is assigned to at least one of the elements (18). The optical duct (24) is assigned an infrared detector (28) that is designed to detect infrared radiation (30) from the at least one element (18) through the optical duct (24) to determine a temperature (T) of the at least one element (18).