Patent ID: 6988481

Claim:
A system for controlling an internal combustion engine having a plurality of cylinders and mounted on a vehicle, operation of the engine being switchable, based on at least load of the engine, between full-cylinder operation during which all of the cylinders are operative and cut-off-cylinder operation during which some of the cylinders are non-operative, and having a running controller that performs running control including at least one of cruise control during which the vehicle is controlled to run at a desired vehicle velocity and preceding vehicle follow-up control during which the vehicle is controlled to run at a desired vehicle velocity to maintain a desired inter-vehicle distance from a preceding vehicle, in response to an instruction of an operator, comprising: velocity error determiner that determines whether a velocity error between a detected vehicle velocity and the desired vehicle velocity is equal to or smaller than a velocity error threshold value; load determiner that determines whether load of the engine is equal to or smaller than a load threshold value; running condition determiner that determines that running condition of the vehicle is stable when the velocity error is equal to or smaller than the velocity error threshold value and when the load of the engine is equal to or smaller than the load threshold value; and engine operation controller that controls to switch the operation of the engine to the cut-off-cylinder operation if the running condition of the vehicle is determined to be stable when the running control is performed by the running controller.