Patent ID: 7136739

Claim:
An engine control device for detecting misfire of an engine of a motor vehicle, comprising: crank angle detection means for detecting a crank angle of the engine; angular velocity calculation means for calculating a pre-combustion angular velocity and a post-combustion angular velocity based on the crank angle detected by the crank angle detection means, the pre-combustion angular velocity being an angular velocity at a first crank angle at which rotation speed of the engine is close to a minimum value within one combustion cycle of each cylinder of the engine, the post-combustion angular velocity being an angular velocity at a second crank angle at which the rotation speed of the engine is close to a maximum value within the one combustion cycle; rotation variation amount calculation means for calculating, based on the pre-combustion and post-combustion angular velocities of the one combustion cycle, an amount of rotation variation caused between the first and second crank angles; misfire determination means for comparing the rotation variation amount calculated by the rotation variation amount calculation means with a predetermined misfire criterion value, to determine whether or not misfire has occurred in the one combustion cycle; and counter-misfire control means for performing a required operation when it is judged by the misfire determination means that misfire has occurred.