As for the diesel engine, it does not need the ignition system required by gasoline engines.
Diesel engines experience strong compression of the incoming air, accompanied by a significant increase in temperature. When fuel is injected into the compressed and heated air, it self-ignites.
The RENAUL MEGANE petrol engines are equipped with an ignition system, the control unit memory of which contains parametric data determined during bench and road engine tests. The control unit gives a command to the ignition coils by sending the appropriate pulses. The ignition system is synchronized based on the signals from the pulse sensor coming to the control unit. The pulse sensor is installed on the gearbox flange and reads the number of revolutions of the engine crankshaft.
Cars with 1.4 liter petrol engine (E7J). The high voltage generated by the ignition coil is supplied to the corresponding spark plug through the distributor rotor via the high voltage wire. A spark jumps between the spark plug electrodes, igniting the air-fuel mixture in the cylinder.
Cars with a 1.6-liter (K7M) and 2.0-liter gasoline engine. The ignition system does not have a distributor. Distribution of ignition voltage between the cylinders is performed electronically. High voltage is generated by two dual coils mounted on the cylinder head.
Cars with a 1.4-/1.6-liter petrol engine (K4J/ K4M). This engine has basically the same ignition system as the 1.6 and 2.0 liter petrol engines. The difference is that each spark plug has its own ignition coil. All four coils are built into the spark plug tips, which in turn are mounted on the spark plugs, so there are no high-voltage wires.
To determine the optimal ignition timing angle, the system control unit uses the parametric data stored in its memory, which allows the system to quickly and easily adapt to different operating conditions (see illustration 1.0).
1.0 Schematic representation of parametric data stored in the memory of the ignition system control unit
1 - ignition timing angle
2 - operating load
3 - engine speed
The ignition timing is also determined using knock sensors. Due to the fact that fuel consumption at high compression is minimal, the compression of modern engines is quite high. However, high compression can lead to uncontrolled ignition, called knock combustion of fuel. Knock combustion of fuel has a negative effect on the condition of the engine, which is damaged over time. To avoid knock combustion of fuel, it is necessary to install a knock sensor that provides a later ignition timing.
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All components of the ignition system are adjusted relative to each other and ensure that the ignition timing angle remains constant.
When repairing the ignition system, certain safety measures must be followed to prevent injury to service personnel or damage to the system itself.