APPARATUS AND METHOD FOR DETECTING ABNORMAL AIR-FUEL RATIO VARIATION AMONG CYLINDERS OF MULTI-CYLINDER INTERNAL COMBUSTION ENGINE

摘要

An apparatus for detecting abnormal air-fuel ratio variation among cylinders of a multi-cylinder internal combustion engine includes: a catalyst element that oxidizes hydrogen contained in exhaust gas to remove the hydrogen; a first air-fuel ratio sensor that detects an air-fuel ratio of exhaust gas that has not passed through the catalyst element; a second air-fuel ratio sensor that detects an air-fuel ratio of exhaust gas that has passed through the catalyst element; and a unit that determines whether abnormal air-fuel ratio variation among the cylinders has occurred based on an amount by which a value detected by the second air-fuel ratio sensor is leaner than a value detected by the first air-fuel ratio sensor