Diesel engine preheating device

According to practical experience, when cold starting, diesel engines are difficult to go out only in the first stage. Direct injection engines, such as those in the Mondeo, start even in winter at our latitudes «politely», However, in severe frost they work hard, their first signs of life completely without a preheating device may not appear.

To do this, powerful glow plugs during the start-up period of a cold engine heat the compressed air in the cylinders and thereby speed up the ignition process. The glow plugs are located on the side of the cylinder head and, like the preheat warning light on the instrument panel, are under the supervision of the engine control unit (RSM). To determine the duration of the warm-up, the PCM receives during the warm-up period from the temperature sensor of the cylinder head (SNT) temperature signal. The lower the temperature, the more intense the initial warm-up period: the maximum warm-up time is 8 seconds, assuming average temperatures of -20°C prevail. At an engine temperature above 80°C, the heating device is completely switched off.

As soon as the cold engine starts, the period of additional heating of the glow plugs begins. This improves idling behavior and minimizes hydrocarbon emissions after a cold start. The maximum duration of this period is 30 seconds at -20°C or colder outside temperatures. At engine temperatures above 50°C, this period is not carried out, as well as at engine speeds above 2500 rpm - this lengthens the life of the glow plugs.

Each cylinder is heated by a separate candle: Mondeo glow plugs have a very compact design - they work without their own temperature control. This is not a disadvantage, since the fresh air drawn in does not allow the candles to burn out - the maximum temperature here is limited to about 1050°C.

Manifested failures and unevenness in the system «collects» electronic memory – its content can only be read or erased in a contract workshop.

PRACTICAL ADVICE

Defective preheater Defects in the preheating device of a turbodiesel become noticeable, probably only in bitter cold (-15°С). Only in this situation, the diesel unit is reluctant to do its job without outside help. With appropriate attention, possible defects can be detected already at an early stage: during a cold start, pay attention to the exhaust gas. If unpleasant blue pillars of smoke leave the exhaust pipe, you should read the information from the drive at your bus station - blue smoke signals «cold» combustion. Small clouds, of course, should not bother you.