As already mentioned, the ignition system operates on carburettor engine electronic control unit or the injection system. Only in gasoline engines without catalyst the conventional distributor which regulates the ignition timing under the influence of centrifugal forces and underpressure, which are selected according to engine speed and engine load. With increasing engine speed the centrifugal weights in the carburetor move centrifugally outwards against the force of a small return spring is rotated with respect to the adjusting cam shaft of the distributor, so that the imposition of a pre-ignition. A vacuum unit is connected to the carburetor small conduit. At high vacuum, the imposition of a pre-ignition, but set back when the engine is under heavy load.
The drive of the distributor of ignition is carried out from one of the camshaft. In injection engines ignition timing governed by an electronic control unit to provide the best for fuel and air under all operating conditions. These adjustments are recorded in the memory of the ignition control device. The control unit receives information such as the injection duration and position of the crankshaft and controls the switching transistors in a given moment. Adjust the ignition timing is set to the optimum value when starting the engine, when it is warming up, idling, acceleration and when coasting.