Motor control with valve actuation monitoring using a camshaft position detection

A system or method for controlling a multi-cylinder internal combustion engine operable with at least a selectively deactivated valve or cylinder in an operation with reduced capacity, involves monitoring of the valve operating by analyzing the camshaft position, to detect a valve actuator, which in terms of a current cylinder state (enabled or disabled) is inconsistent, and controlling the engine in response to detecting the inconsistent operation. The cam position may be used to generate a replacement signal indicative of an intake / exhaust valve lift and is generated using a camshaft sensor tooth deviation relative to an expected position of the teeth or reference tooth position for a corresponding crankshaft position and compared to a corresponding threshold value. The replacement signal indicative of a valve lift can also be generated by the pattern matching or the correlation of one or more reference patterns tooth position with a measured or inferred tooth position pattern.