Patent ID: 7603994
Filing Date: 2009-10-20
Classification: F02D,F02P,Y02T

Abstract:
1. An abnormality diagnosis device of a multi-cylinder internal combustion engine having a junction where exhaust gases discharged respectively from a plurality of cylinders converge, the abnormality diagnosis device comprising: an air-fuel ratio sensing means provided downstream of the junction for sensing an air-fuel ratio of the exhaust gas; a diagnosing means for diagnosing presence or absence of an abnormality in an individual air-fuel ratio of each cylinder based upon a sensing value of the air-fuel ratio sensing means; a determining means for determining whether a quantity of the exhaust gas discharged from each cylinder per exhaust stroke is equal to or greater than a first predetermined value; and a prohibiting means for prohibiting the diagnosis when the determining means determines that the quantity of the exhaust gas is less than the first predetermined value.