Abstract: A fuel injection amount control device is used for an internal combustion engine. A secondary air supply device supplies secondary air into an exhaust passage of the internal combustion engine. Flow amount calculating circuitry calculates a secondary air flow amount. The secondary air flows into the exhaust passage. Target air fuel ratio setting circuitry sets a target air fuel ratio when secondary air is supplied. Fuel amount correcting circuitry corrects a fuel injection amount in accordance with a current value of the secondary air flow amount such that the air fuel ratio on a downstream side of an inlet of secondary air in the exhaust passage becomes the target air fuel ratio when secondary air is supplied. Target changing circuitry monitors increase and decrease in the secondary air flow amount. The target changing circuitry changes the target air fuel ratio to one of a rich side and a lean side in accordance with the increase and decrease in the secondary air flow amount.

Abstract: A fuel injection amount control device is used for an internal combustion engine. A secondary air supply device supplies secondary air into an exhaust passage of the internal combustion engine. A flow amount calculating means calculates a secondary air flow amount. The secondary air flows into the exhaust passage. A target air fuel ratio setting means sets a target air fuel ratio when secondary air is supplied. A fuel amount correcting means corrects a fuel injection amount in accordance with a current value of the secondary air flow amount such that the air fuel ratio on a downstream side of an inlet of secondary air in the exhaust passage becomes the target air fuel ratio when secondary air is supplied. A target changing means monitors increase and decrease in the secondary air flow amount. The target changing means changes the target air fuel ratio to one of a rich side and a lean side in accordance with the increase and decrease in the secondary air flow amount.