| 摘要 |
PURPOSE: A method of detecting misfire of an engine for a vehicle is provided to exactly sense misfire and detect a cylinder with misfire, with using response characteristics to a sudden concentration change of a wide range oxygen sensor. CONSTITUTION: An engine control unit outputs a control signal, receives engine RPM(Revolutions Per Minute), coolant temperature, suction air flow, wide range oxygen, an angle of a crank, and a phase sensor signal, and detects response characteristics to a sudden concentration change of a wide range oxygen sensor(S100,S110,S120). The engine control unit receives oxygen concentration of exhaust gas, to decide misfire, to calculates voltage change gradient of the signal of the wide range oxygen sensor, and multiplies the calculated value by a corrective factor1(S130,S140). The engine control unit decides whether the signal change gradient of the wide range oxygen sensor is greater than a critical value 2(S150). If a phenomenon that the wide range oxygen sensor signal change gradient exceeds the critical value happens more than twice, the engine control unit calculates phase difference between the second peak value of the wide range oxygen sensor signal variable ratio and the phase sensor signal(S170). The engine control unit decides a cylinder having misfire through the calculated phase difference and decides the form of misfire generation through measurement of signal gradient peak generation frequency(S180).
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