Importance

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Abstract

An engine combustion controller for an engine having a fuel supply system selects an engine combustion mode from one of lean combustion, in which an air fuel mixture leaner than a stoichiometric mixture is burned, and stoichiometric combustion, in which a stoichiometric mixture is burned, in accordance with an operating state of the engine and controls, via feedback, the air fuel ratio of the air fuel mixture when the stoichiometric combustion is performed using air-fuel ratio compensating value that are based on the composition of the engine exhaust gas. A preliminary tester checks the fuel supply system and determines that the fuel supply system is in a normal state when certain preliminary test conditions are satisfied, which includes checking the feedback compensating value. A prohibiter prevents lean combustion when the preliminary tester determines that the state of the fuel supply system is ambiguous. A main tester tests the fuel supply system and determines that the fuel supply system is in an abnormal state when certain main test conditions are satisfied, which includes checking the feedback compensating value.

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First Claim