Abstract: A method for detecting a misfiring cylinder is characterized by: performing frequency analysis on a torsional vibration signal from an internal-combustion engine system to extract an amplitude and a phase of a fundamental frequency component; comparing the amplitude of the fundamental frequency component with the amplitude of the torsional vibration signal to determine whether misfiring has occurred; calculating, when the misfiring is determined to occur, an explosion angle of a misfiring cylinder by using crank angle displacement at which the fundamental frequency component has a maximum value, and a phase of a fundamental frequency component with excitation force; and comparing the calculated explosion angle with an explosion angle of explosion order to detect the position of the misfiring cylinder.

Abstract: A method for detecting a misfiring cylinder is characterized by: performing frequency analysis on a torsional vibration signal from an internal-combustion engine system to extract an amplitude and a phase of a fundamental frequency component; comparing the amplitude of the fundamental frequency component with the amplitude of the torsional vibration signal to determine whether misfiring has occurred; calculating, when the misfiring is determined to occur, an explosion angle of a misfiring cylinder by using crank angle displacement at which the fundamental frequency component has a maximum value, and a phase of a fundamental frequency component with excitation force; and comparing the calculated explosion angle with an explosion angle of explosion order to detect the position of the misfiring cylinder.