Controller and control method for internal combustion engine

A control method for an internal combustion engine, the internal combustion engine including ignition devices, fuel injection valves, and an exhaust purifying device, which purifies exhaust gas discharged from a plurality of cylinders, the controller method comprising:

• learning a degree of variation in an injection amount of the fuel injection valves provided for the respective cylinders when the fuel injection valves are operated to control air-fuel ratios of the respective cylinders to be equal to each other;
• a first advancement requesting process of causing a request for ignition timing to be more advanced when the degree of variation is great than when the degree of variation is small;
• a second advancement requesting process of causing the request for the ignition timing to be more advanced when a torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small;
• and
• controlling the ignition timing in accordance with the request of the more advanced one of the first advancement requesting process and the second advancement requesting process.

A non-transitory computer readable memory medium that stores a program that causes a processor to execute a control process for an internal combustion engine, the internal combustion engine including ignition devices, fuel injection valves, and an exhaust purifying device, which purifies exhaust gas discharged from a plurality of cylinders, the control process includes

• learning a degree of variation in an injection amount of the fuel injection valves provided for the respective cylinders when the fuel injection valves are operated to control air-fuel ratios of the respective cylinders to be equal to each other;
• a first advancement requesting process of causing a request for ignition timing to be more advanced when the degree of variation is great than when the degree of variation is small;
• a second advancement requesting process of causing the request for the ignition timing to be more advanced when a torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small;
• and
• controlling the ignition timing in accordance with the request of the more advanced one of the first advancement requesting process and the second advancement requesting process.