In usual system of ignition the coil of ignition develops a high-tension current and the distributor of ignition transfers this current in demanded time to the corresponding spark plug.
In contactless system of ignition the sensor of provision of a camshaft and the sensor of an angle of rotation of a cranked shaft hand over to the control unit the engine information in what cylinder it is necessary to submit tension of ignition. The control unit the engine gives a signal to the corresponding coil of ignition which develops a high-tension current and transfers this current to a spark plug.
In contactless system of ignition the impulse of ignition moves at once on two spark plugs, one on the compression step, one on an exhaust step – the ignition spark on a step of an exhaust does not render any value for operation of the engine and consequently is spent for nothing. Cylinders are grouped according to an operating procedure of cylinders. For example, an operating procedure of cylinders – 1–3–4–2. Each coil of ignition actually consists of the 2nd separate high-voltage windings which submit a spark to two cylinders everyone (one to cylinders No. 1 and 4, and another to cylinders No. 2 and 3).
If at such system of ignition to connect an inductive tachometer to a high-voltage wire of a spark plug, it will show frequency of rotation of a cranked shaft of the engine twice more actual frequency of rotation (i.e. 1600 mines-1, instead of the actual 800 mines-1).
Electronic system of an advancing of ignition
Installation of a corner of an advancing of ignition is defined and established by the control unit of the engine based on signals from various sensors and switches.
The control unit the engine changes corner installation an ignition advancing according to frequency of rotation of the engine, amount of the arrived air, temperature of cooling liquid and other conditions.
Corner of an advancing of ignition on frequency of idling: 8±5 ° to VMT (6 °± 5 ° for Europe).
The corner of an advancing of ignition is not regulated.