| 摘要 |
PROBLEM TO BE SOLVED: To distinctly diagnose the malfunction of a fuel system, the malfunction of a fuel nature sensor, and the malfunction of a fuel supply determining means. SOLUTION: This malfunction diagnosing apparatus includes the fuel supply determining means for determining whether fuel is supplied into a fuel tank 30 or not, in accordance with a fuel level detected by a fuel level detector 45, and a fuel nature sensor 37 for detecting the nature of fuel (alcohol concentration, etc.) to be supplied from the fuel tank 30 to a fuel injection valve 21. During engine operation, an air-fuel ratio correction amount is set depending on a deviation (an air-fuel ratio shift amount) between a target air-fuel ratio and an actual air-fuel ratio and the nature of fuel detected by the fuel nature sensor 37, and corrects the fuel injection amount of the fuel injection valve 21 with the air-fuel ratio correction amount. In accordance with the combination of the determination result of the fuel supply determining means, the detection result of the fuel nature sensor 37, and the air-fuel ratio correction amount (or the air-fuel ratio shift amount), the malfunction of the fuel supply determining means, the malfunction of the fuel nature sensor 37, and the malfunction of the fuel system ranging from the fuel tank 30 to the fuel injection valve 21 are distinctly diagnosed. COPYRIGHT: (C)2010,JPO&INPIT
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