Glow plug system
The glow device should heat the combustion chamber from approx. +20°C, particularly in the case of secondary combustion chamber processes, but also in some cases with direct injection from approx. -5°C during cold
start and cold running. This positively influences the diesel engine's starting and running characteristics (noise, exhaust emissions).
Since the glow plugs now remain switched on even after a cold start, the term "preheating system" is no longer appropriate. During preheating, current is applied to the glow plugs (0.5 - 2 ohms) of the individual cylinders.
To keep the preheating time for the driver as short as possible, some control units switch on the power as soon as the driver's door is opened. The engine can be started when the indicator light goes out.
The system also shuts down if the engine doesn't start within a certain time. The afterglow time is also temperature-controlled. This is done to prevent the loud knocking of the diesel engine during cold start. This is caused
by excessive ignition delay (the time between the start of injection and ignition).
Truck engines in particular can sometimes do without a glow plug system or have a flame start system. This continuously burns a small amount of diesel fuel in the intake tract, thereby heating the intake air.
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