INTER-CYLINDER AIR-FUEL RATIO DISPERSION ABNORMALITY DETECTOR

摘要

PROBLEM TO BE SOLVED: To identify abnormal cylinders if abnormal cylinders causing a dispersion abnormality is two cylinders.SOLUTION: Parameters correlating to an output fluctuation degree of an air-fuel ratio sensor installed in an exhaust path common to a plurality of cylinders are calculated and an inter-cylinder air-fuel ratio dispersion abnormality is detected on the basis of the calculated parameters. Step (A) of forcibly changing fuel injection quantities for two out of the plurality of cylinders and calculating the parameter; step (B) of changing the two cylinders and repeating the step (A); and step (C) of identifying the two cylinders causing the dispersion abnormality on the basis of a plurality of parameters calculated in the steps (A) and (B) are executed.