Patent ID: 8033098

Claim:
A control method for an internal combustion engine, comprising: performing a throttle operation for controlling an amount of air taken in a cylinder by regulating an opening amount of a throttle valve, the throttle valve being provided in an intake passage of the internal combustion engine; performing a non-throttle operation for controlling the amount of air taken in the cylinder by holding the opening amount of the throttle valve to a predetermined amount and by operating a variable valve system, the variable valve system changing at least one of a valve-open duration and a valve lift amount of an intake valve of the internal combustion engine; detecting or estimating a temperature of a catalyst, the catalyst being provided in an exhaust passage of the internal combustion engine; and prohibiting the non-throttle operation when the temperature of the catalyst is below a predetermined value so that the throttle operation warms the catalyst, and permitting the non-throttle operation when the temperature of the catalyst is equal to or higher than the predetermined value.