The present invention provides a method of detecting internal combustion engine misfiring. The method includes mixed rate sampling of crankshaft angular velocity for a plurality of cylinder firing events to generate a crankshaft angular velocity signal and a cylinder firing synchronization signal. The apparatus for executing the method comprises a crankshaft in operative relation with the internal combustion engine. A crankshaft sensor wheel is rotatably triggered by the crankshaft and includes a plurality of predetermined sensor indicators disposed at least at two different angular widths. A sensor is positioned adjacent to the wheel for sensing the passage of each indicator in producing a signal pulse having a duration corresponding to the angular width of the sensed indicator in response thereto. A counter determines the time intervals between signal pulses generated by the sensor including a synchronization signal time interval and an RPM signal time interval. The synchronization signal time interval is then utilized to calculate a plurality of crankshaft angular velocities for a plurality of RPM indicators replaced by a synchronization indicator. A misfire detector then determines if a misfire has occurred by interpreting a series of data points developed from the plurality of crankshaft angular velocities.