Engine controller

Abstract

To appropriately execute sub-feedback of air-fuel ratio feedback control from an early stage.SOLUTION: An engine controller 20 performs air-fuel ratio feedback control through a main feedback that adjusts a fuel injection amount so that a detected value of an exhaust air-fuel ratio from a front air-fuel ratio sensor 24 installed upstream of a three-way catalytic device 18 matches a target air-fuel ratio, and a sub-feedback that alternately switches the target air-fuel ratio of the main feedback between a lean-side target air-fuel ratio and a rich-side target air-fuel ratio based on a detection result of a rear air-fuel ratio sensor 25 installed downstream of the three-way catalytic device 18. When the engine 10 is in a cold operation, the engine controller sets the lean-side target air-fuel ratio to a value that is leaner than when the engine is in warm operation.SELECTED DRAWING: Figure 1

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