In order to facilitate cold starting, diesel engines are equipped with a pre-heating system, the components of which are four glow plugs, a control unit, a warning lamp mounted in the instrument panel and a set of connecting electrical wiring.
Glow plugs are miniature heating elements enclosed in a metal casing.
At one end of the glow plug there is a probe of the working element, at the other there is an electrical contact. Each of the swirl chambers/cylinder mouth is equipped with an individual glow plug. The working element of the spark plug is located coaxially with the jet of injected fuel. When the spark plug is energized, the injected fuel heats up, reaching the optimum combustion temperature before entering the cylinder.
The length of the preglow period is determined by the system control unit, which monitors the engine temperature from the CTS reading and adjusts the spark plug energization time to suit specific conditions.
A control lamp mounted in the instrument panel informs the driver about the functioning of the system. when the mixture temperature necessary for successful engine start is reached, the lamp turns off, however, power continues to be supplied to the candles for some more time. If there is no attempt to start within the specified period, the candles are turned off to avoid battery replanting and burnout of the working heating elements. On some models, if the control unit detects a malfunction of the preheating system, the control lamp continues to burn even when the engine is running.
Strictly speaking, the preheating system is activated by turning the ignition key to position II. However, Felicia models are additionally equipped with a pre-heating system, which is launched when the driver's door is opened and then closed. Naturally, the system is activated once for each engine start. If there is no attempt to start the engine within a certain period of time after opening and closing the driver's door, the system will not re-activate when the door is opened.
Glow plugs continue to function for up to 3 minutes after starting the engine, which improves the ignition efficiency of the mixture, reduces noise, stabilizes idle speed and reduces exhaust emissions.