Self-diagnostic device in fuel supplier for internal combustion engine


PURPOSE: To make an efficient self-diagnosis of faulty and deteriorated parts in a fuel supply system. CONSTITUTION: An air-fuel ratio feedback correction coefficient LMD for correcting a basic fuel injection amount Tp so as to obtain actual air-fuel ratio to approach a target is set. A rich directional control amount SUMR and a lean directional control amount SUML by the above-mentioned correction coefficient LMD in a predetermined period are respectively obtained to compare (S32, S33) the above-mentioned control amounts SUMR, SUML respectively with predetermined values LS1, SL2, and when at least one of the above- mentioned control amounts SUMR, SUML is the predetermined value or more, a fuel supply system is judged (S34) improper. Here, when a transient operation rate is a predetermined level or more, zero is set to a diagnosis permissible flag Fd to inhibit (S31) diagnosis based on the above-mentioned control amount, and a wrong diagnosis, influenced by air-fuel ratio displacement at transient time, is avoided. COPYRIGHT: (C)1992,JPO&Japio




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