INTERNAL COMBUSTION ENGINE CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a technique capable of suppressing combustion from being made unstable after an air-fuel-ratio feedback control and a fuel property learning control are halted and then resumed in an internal combustion engine using fuel whose properties possibly vary for every filling.SOLUTION: An air-fuel-ratio feedback control is implemented using a first correction value determined in response to a deviation between a detected air-fuel ratio of an air-fuel mixture and a target air-fuel ratio and a second correction value determined in response to fuel properties. Furthermore, a fuel property learning control is implemented to correct the first correction value and the second correction value in such a manner that an absolute value of the first correction value is equal to or smaller than a threshold if the absolute value of the first correction value is greater than the threshold after fuel filling. A combustion-continuable correction value range that is a range of the second correction value so as to make the air-fuel ratio of the air-fuel mixture fall in an air-fuel ratio range in which combustion can continue is stored, and the second correction value is set to a value within the combustion-continuable correction value range if the air-fuel-ratio feedback control and the fuel property learning control are halted.SELECTED DRAWING: Figure 3