Patent ID: 6273075
Filing Date: 2001-08-14
Classification: F02D

Abstract:
A method for detecting a malfunction of a cylinder in a car, comprising the steps of:(a) measuring an output value of a wide range oxygen sensor that detects density of oxygen in the exhaust gas at a crank angle during a predetermined cycle and computing an ensemble average value when an engine of a car is in normal status;(b) finding maximum and minimum values of the computed ensemble average value;(c) determining a difference between the maximum and minimum values to be a malfunction of the cylinder when the difference is greater than a predetermined reference value set for determining a malfunction of a cylinder, and detecting a position of the cylinder, via the crank angle, at the maximum or minimum values; and(d) increasing or decreasing injected fuel at the detected position, and determining a malfunction of the cylinder according to whether the difference between the maximum and minimum values of the ensemble average values during a predetermined engine cycle decreases more than a previously set value.