The engine control unit provides excitation of the primary windings of the coils by connecting them with «weight». The moment the control signal is applied to the ignition coils is determined by the ECU based on signals from the crankshaft position sensor. When voltage is applied to and removed from the primary winding, a high voltage pulse is induced in the secondary winding, which is applied to the corresponding spark plug.
Pic. 2.254. Ignition coil
Pic. 2.255. Ignition coil and ECU connection diagram
Pic. 2.256. Fuel pump connection diagram
Conditions for storing fault codes
The ECU stores the P0300 code and the engine control system malfunction indicator lamp lights up if 2 misfires of the mixture occur per 100 crankshaft revolutions in two driving cycles.
The misfire rate is measured every 200 crankshaft revolutions under the following conditions:
- the rate of change of the crankshaft speed does not exceed 1000 min-1 per second;
- crankshaft speed is within 600–4000 min-1;
- motor load above 2 milliseconds;
- fuel cutoff does not occur;
- the starter does not work;
- the car is moving on a flat road (acceleration sensor determines accelerations no more than 0.3 g).
If the misfire rate increases by 5% to 25% per 200 crankshaft revolutions, there is a risk of failure of the catalytic converter, and the engine management system malfunction lamp lights up first flashing and then steady light. If the misfire rate is high enough, the temperature of the catalytic converter can reach 1950°C. If the ECU remembers this code, it indicates a malfunction in the ignition circuit of the corresponding cylinder.