A method of detecting misfire in an internal combustion engine , the engine having a plurality of cylinders , a corresponding plurality of pistons , and a shaft operatively connected to the plurality of pistons , the shaft having a longitudinal axis about which the shaft rotates, the method comprising: sensing a temporal signature of a lateral displacement of the engine via an acceleration sensor , the acceleration sensor sensing the lateral displacement in at least one direction, the at least one direction being non-parallel relative to the longitudinal axis of the shaft , the acceleration sensor being connected to a control unit , the temporal signature being decomposable into a plurality of frequencies, associated magnitudes, and associated phase angles, each of the plurality of frequencies being associated with a corresponding one of a plurality of orders of the engine ; sending a signal corresponding to the temporal signature of the lateral displacement from the acceleration sensor to the control unit ; processing the signal with the control unit , the processing comprising: performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency, the predetermined frequency being associated with one of the plurality of orders of the engine , the one of the plurality of orders being representative of engine displacement due to in-cylinder pressures; and determining that misfiring in at least one of the plurality of cylinders has occurred based on the magnitude of the predetermined frequency. sensing a temporal signature of a lateral displacement of the engine via an acceleration sensor , the acceleration sensor sensing the lateral displacement in at least one direction, the at least one direction being non-parallel relative to the longitudinal axis of the shaft , the acceleration sensor being connected to a control unit , the temporal signature being decomposable into a plurality of frequencies, associated magnitudes, and associated phase angles, each of the plurality of frequencies being associated with a corresponding one of a plurality of orders of the engine ; sending a signal corresponding to the temporal signature of the lateral displacement from the acceleration sensor to the control unit ; processing the signal with the control unit , the processing comprising: performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency, the predetermined frequency being associated with one of the plurality of orders of the engine , the one of the plurality of orders being representative of engine displacement due to in-cylinder pressures; and determining that misfiring in at least one of the plurality of cylinders has occurred based on the magnitude of the predetermined frequency. performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency, the predetermined frequency being associated with one of the plurality of orders of the engine , the one of the plurality of orders being representative of engine displacement due to in-cylinder pressures; and determining that misfiring in at least one of the plurality of cylinders has occurred based on the magnitude of the predetermined frequency. <EOS>