Abstract: A control apparatus performs a diagnosis process for determining whether or not catalyst warm-up control is abnormal by determining whether or not an ignition timing that is set during the performance of catalyst warm-up control is a timing advanced by a threshold or more. The threshold is a value that is set to a timing more advanced than the ignition timing that is set during the performance of catalyst warm-up control by a predetermined margin. The control apparatus performs a setting process for setting the threshold based on a start-up coolant temperature such that the margin becomes larger when the start-up coolant temperature is low than when the start-up coolant temperature is high.

Abstract: A control apparatus performs a diagnosis process for determining whether or not catalyst warm-up control is abnormal by determining whether or not an ignition timing that is set during the performance of catalyst warm-up control is a timing advanced by a threshold or more. The threshold is a value that is set to a timing more advanced than the ignition timing that is set during the performance of catalyst warm-up control by a predetermined margin. The control apparatus performs a setting process for setting the threshold based on a start-up coolant temperature such that the margin becomes larger when the start-up coolant temperature is low than when the start-up coolant temperature is high.

Abstract: An engine system includes an engine that, a fuel supply device, and an electronic control unit. The electronic control unit is configured to control the fuel supply device and to perform operation control of the engine by adjusting an injection ratio between fuel injection from an in-cylinder injection valve and a port injection valve according to the operation state of the engine. The electronic control unit is configured to perform imbalance determination. The electronic control unit is configured to change a region of fuel injection from a first fuel injection region to a second fuel injection region when the electronic control unit determines that a lean imbalance is occurred with respect to the fuel injection in which the fuel injection from the port injection valve is performed.

Abstract: An engine system includes an engine that, a fuel supply device, and an electronic control unit. The electronic control unit is configured to control the fuel supply device and to perform operation control of the engine by adjusting an injection ratio between fuel injection from an in-cylinder injection valve and a port injection valve according to the operation state of the engine. The electronic control unit is configured to perform imbalance determination. The electronic control unit is configured to change a region of fuel injection from a first fuel injection region to a second fuel injection region when the electronic control unit determines that a lean imbalance is occurred with respect to the fuel injection in which the fuel injection from the port injection valve is performed.

Abstract: A multi-cylinder internal combustion engine includes: a first fuel injection valve that injects fuel into each cylinder; a second fuel injection valve that injects fuel into an intake passage; and an exhaust recirculation device that causes some of exhaust flowing in an exhaust passage to recirculate into the intake passage. A control device is used in the multi-cylinder internal combustion engine. The control device limits recirculation of exhaust into the intake passage by the exhaust recirculation device when imbalance determination is conducted during engine operation by fuel injection from the first fuel injection valve only, compared to when imbalance determination is conducted during engine operation involving fuel injection from the second fuel injection valve.

Abstract: A multi-cylinder internal combustion engine includes: a first fuel injection valve that injects fuel into each cylinder; a second fuel injection valve that injects fuel into an intake passage; and an exhaust recirculation device that causes some of exhaust flowing in an exhaust passage to recirculate into the intake passage. A control device is used in the multi-cylinder internal combustion engine. The control device limits recirculation of exhaust into the intake passage by the exhaust recirculation device when imbalance determination is conducted during engine operation by fuel injection from the first fuel injection valve only, compared to when imbalance determination is conducted during engine operation involving fuel injection from the second fuel injection valve.