An intake air control for an internal-combustion engine

The present invention provides an intake air control that is capable of suppressing the exhaust emission at engine startup and quickly activating a catalyst after engine startup. An engine has a variable valve actuation mechanism for continuously adjusting at least a lift amount of an intake valve to control an intake air amount. At startup of the engine, the lift amount is set in accordance with the number of times that a piston in a cylinder of the engine has passed through a top dead center until a rotational speed of the engine reaches an idle rotational speed. After an engine water temperature becomes greater than a predetermined value, the lift amount is corrected using a proportion term that is determined based on the engine rotational speed and an integral term that is determined based on a difference between the engine rotational speed and the idle rotational speed until the engine rotational speed reaches the idle rotational speed. After the engine rotational speed reaches the idle rotational speed, the lift amount is gradually changed to an idle lift amount while maintaining the idle rotational speed through an ignition timing control. The idle lift amount is a lift amount under which the idle rotational speed is able to be maintained.