Electronic ignition coil

Electronic ignition coil

 

1---Spark plug cables

2---EI ignition coil

3---Spark plug

 

The electronic ignition system is a fully electronic, distributorless ignition system with no moving parts on the high-voltage side.
The electronic ignition system is integrated into the PCM.
With an electronic ignition system, high-voltage distribution to the individual cylinders is realized via special double spark coils. The signal from the CKP sensor forms the basis for ignition timing calculations. From an ignition map, the PCM determines the optimum closing time and current rise of the primary current circuit of the ignition coil with switching carried out via end-stages in the PCM. The ignition timing is determined by the PCM on the basis of the engine operating conditions. Once the ignition timing has been determined, the PCM interrupts the current supply to the primary circuit of the ignition coil, triggering a high voltage which causes a spark in the cylinder via the ignition cable and spark plug.
The spark plugs are activated in pairs (cylinders 1 and 4, and cylinders 2 and 3) and send a strong main spark to the cylinder in the compression cycle and a weak secondary spark to the cylinder in the exhaust cycle. The main spark is generated automatically in the cylinder that is in the compression cycle, because a higher resistance exists between the electrodes on account of the high compression.
On one spark plug a spark jumps across from the centre electrode to the earth electrode, and on the other spark plug from the earth electrode to the centre electrode.