| 摘要 |
PROBLEM TO BE SOLVED: To diagnose abnormality of a fuel supply system with high accuracy even when the internal temperature of an engine room is high. SOLUTION: When fuel supply system abnormality diagnosis execution conditions are materialized, the air-fuel ratio discrepancy index value is compared with the lean/rich abnormality judgment value to diagnose the abnormality of a fuel supply system. When the internal temperature of an engine room is the set temperature or higher, the high temperature time lean abnormality judgment value KHL is set to the value shifted to the leaner side than the normal time lean abnormality judgment value KLL, and the high temperature time rich abnormality judgment value KHH is set to the value shifted to the richer side than the normal time rich abnormality judgment value KLH, taking account of circumstances of a basic air-fuel ratio discrepancy becoming large. The presence of abnormality of the fuel supply system (that is, the abnormal discrepancy of the air-fuel ratio) can therefore be diagnosed while preventing a wrong diagnosis even when the internal temperature of the engine room is high, and the early discovery of abnormality and prevention of a wrong diagnosis can be reconciled. |
