Importance

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Abstract

An engine misfiring diagnosis device includes: a misfiring diagnosis value calculator that calculates a misfiring diagnosis value for determination of misfiring, based on an amount of rotational fluctuations among cylinders; a reference determination threshold calculator that calculates a reference determination threshold for determining occurrence of misfiring, based on an engine operating state; a first misfiring determiner that compares the misfiring diagnosis value with the reference determination threshold, and determines misfiring of a cylinder being diagnosed; and a second misfiring determiner that, if the first misfiring determiner has determined misfiring is occurring, performs re-determination regarding misfiring for the cylinder being diagnosed, based on a difference between a value obtained by correcting the misfiring diagnosis value of the cylinder being diagnosed with a rotational fluctuation correction value based on the engine operating state, and the misfiring diagnosis values of the cylinders before and after the cylinder being diagnosed in combustion process order.

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First Claim