INTER-CYLINDER AIR-FUEL RATIO VARIATION ABNORMALITY DETECTION APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To precisely determine whether there is air-fuel ratio variation abnormality among cylinders while suppressing erroneous determination due to an abnormal air-fuel ratio sensor.SOLUTION: In an air-fuel ratio variation abnormality detection apparatus detecting air-fuel ratio variation abnormality among cylinders of an internal combustion engine using an air-fuel ratio sensor comprising a diffusion layer on an electrode, an output change amount of the air-fuel ratio sensor due to an influence of a pressure pulsation of exhaust gas from the internal combustion engine is calculated. The air-fuel ratio variation abnormality is detected in accordance with a value correlated with the output change amount and an output of the air-fuel ratio sensor. As the output change amount, an amplitude of the air-fuel ratio sensor or a value in accordance with the amplitude is used.