Multi-cylinder internal combustion engine, comprising: - an air delivery pipe adapted to convey air to each engine cylinder, - at least one intake valve for each cylinder that controls the communication between said pipe and the combustion chamber of the respective cylinder, - wherein each intake valve is controlled by actuator means for feeding a determined quantity of air into said combustion chamber, said actuator means being adapted to control the respective intake valve independently from the other cylinders and according to variable actuation modes, - injector means for each cylinder adapted to carry out the injection of a determined quantity of fuel into said combustion chamber, - electronic means for controlling the operating conditions of the cylinders, which are adapted to control: -- said actuator means, for adjusting the opening time and stroke of the respective intake valve, -- said injector means, for adjusting said determined quantity of fuel, wherein, when the engine is subject to an operationvariation request from a first operating condition to a second operating condition, said electronic control means are adapted to select the cylinder to which said second operating condition is to be assigned for the first time after said request, on the basis of a programming delay, said programming delay corresponding to the advance time evaluated in number of engine strokes, at which the cylinder is to be programmed with respect to a given instant, so that at said instant, the combustion process of said second operating condition is realized in the cylinder, wherein said electronic control means are arranged in order to define a programming delay that is function of the engine speed only, wherein the programming delay assigned by said electronic control means for a determined engine speed corresponds to the greatest of the actuation times of said injector means and said actuator means for the possible different operating conditions of the engine at said given speed, so that the programming delay associated with said given engine speed is always the same regardless of the new quantities of fuel and air, and of the injection and intake timings, that are requested for the second operating condition. - an air delivery pipe adapted to convey air to each engine cylinder, - at least one intake valve for each cylinder that controls the communication between said pipe and the combustion chamber of the respective cylinder, - wherein each intake valve is controlled by actuator means for feeding a determined quantity of air into said combustion chamber, said actuator means being adapted to control the respective intake valve independently from the other cylinders and according to variable actuation modes, - injector means for each cylinder adapted to carry out the injection of a determined quantity of fuel into said combustion chamber, - electronic means for controlling the operating conditions of the cylinders, which are adapted to control: -- said actuator means, for adjusting the opening time and stroke of the respective intake valve, -- said injector means, for adjusting said determined quantity of fuel, wherein, when the engine is subject to an operationvariation request from a first operating condition to a second operating condition, said electronic control means are adapted to select the cylinder to which said second operating condition is to be assigned for the first time after said request, on the basis of a programming delay, said programming delay corresponding to the advance time evaluated in number of engine strokes, at which the cylinder is to be programmed with respect to a given instant, so that at said instant, the combustion process of said second operating condition is realized in the cylinder, wherein said electronic control means are arranged in order to define a programming delay that is function of the engine speed only, wherein the programming delay assigned by said electronic control means for a determined engine speed corresponds to the greatest of the actuation times of said injector means and said actuator means for the possible different operating conditions of the engine at said given speed, so that the programming delay associated with said given engine speed is always the same regardless of the new quantities of fuel and air, and of the injection and intake timings, that are requested for the second operating condition. -- said actuator means, for adjusting the opening time and stroke of the respective intake valve, -- said injector means, for adjusting said determined quantity of fuel,