Much more complicated in fact. Your car measures constantly the air flow, the temperature of this air, the altitude over the sea level, the velocity of the car, the position in real time of the accelerator and clutch pedals, etc... and then the computer takes all and sends an order to inject in the motor exactly the amount of combustible required for this parameters. Then manages the opening or closing of the valves to allow the gasses go out and those are reintroduced in the motor to be burnt twice. The remain is send then to the anti particles filter and the good parts are allowed to go out, while the problematic ones are sealed in a box.