Startup control method for in-cylinder direct injection spark ignition internal combustion engine, and internal combustion engine system

A startup control method for an internal combustion engine, wherein the internal combustion engine is an in-cylinder direct injection spark ignition internal combustion engine including an intake port provided with a tumble control valve, the startup control method comprising:

• implementing a startup of the internal combustion engine by:
• determining whether or not the startup of the internal combustion engine satisfies a predetermined cold start condition requiring a retard operation of the internal combustion engine for catalyst warmup;
• and
• when determining that the startup of the internal combustion engine satisfies the predetermined cold start condition, performing a startup process;
• wherein the startup process includes:
• closing the tumble control valve;
• after the closing of the tumble control valve, starting to crank the internal combustion engine;
• implementing fuel injection of the internal combustion engine by a single-injection operation during a time period from an initial cycle of combustion of the internal combustion engine to an event that the internal combustion engine rises and reaches a predetermined rotation speed;
• after the event, shifting from the single-injection operation to a multiple-injection operation;
• and
• substantially simultaneously with the shifting to the multiple-injection operation, starting an ignition timing retard.