DPF filter. How not to spoil it?

Increasingly stringent emission standards have forced the use of systems that eliminate soot particles from exhaust gases in all new cars with turbodiesel. Particulate filters work effectively, but they are a typical operational part, which, depending on the way the vehicle is used, makes life after approx. 100-250 thousand. km.
Black smoke from the exhaust pipe has been the hallmark of diesel cars for years. The increasing advancement of propulsion units as well as the tightened emission standards successively limited the scale of this phenomenon. And good. Soot particles can lead to serious respiratory diseases, and with the rapidly growing popularity of cars with turbo diesel, the problem of city smoke has ceased to be a marginal phenomenon.

The breakthrough was 2009, after which all newly-approved passenger cars had to meet the Euro V emission standard. This was possible provided that the exhaust system had a particulate filter. Over the next two years, DPF (diesel particulate filter; French FAP – filter à particules) became standard on all diesel cars.

Particulate filters capture soot from the exhaust gas and collect it. In the periods set by electronics – calculated on the basis of exhaust pressure at the filter inlet and outlet – controlled soot burning is carried out. Cars from the so-called they use special liquids for this process (e.g. Eolys), which reduce the soot flash point. Filters with this principle are often used by French companies. In some engines, e.g. Toyota 2.2 D-CAT, the fuel portion necessary to increase the exhaust gas temperature is fed by an additional, fifth injector. In the case of The dry soot particulate filter (popular in German cars) is burned only by a stream of hot exhaust gases. In order to maintain their temperature at the necessary level, the computer manipulates the amount and time of feeding fuel to the cylinders.

The soot filter cleansing process is most efficient when the engine is under load. This is the case, for example, when driving at 80 km / h and revolutions at 2000-3000 rpm. The process of filter full cleaning takes from several to several minutes. This is not a problem when the car leaves the built-up area from time to time. And when it is operated only in the city? Low-speed driving and an underheated engine cannot clean the filter. To prevent its irreversible clogging, the electronics fight to burn off soot, increasing the dose of fuel fed, which increases the temperature of the exhaust gases.

Cars usually do not inform the driver about the start of firing filter content with a message or indicator. Whoever overlooks the increase in instantaneous fuel consumption, another sound of the engine or the appearance of a characteristic smell and ends the ride, will take the process. The electronics will try to burn the filter again at the first opportunity. Each time a certain amount of unburned diesel oil passes through the cylinders into the oil pan, which leads to a thinning of the lubricant.

If the car is not able to cope with the excess of soot on its own, the engine will go into emergency mode and will inform about the need to burn DPF in the service mode, which can be done in the workshop. You will then pay not only for the service itself. In these situations, service procedures also provide for oil changes.

Due to the aforementioned possibility of thinning oil with fuel, the car user with a DFP filter should regularly check the level of lubricant. If it exceeds the maximum level, the probability of excessive oil vapors entering the cylinders increases by pneumothorax. They will not be fully burned, which in the long run will damage the filter. A similar scenario occurs when an exhausted turbine ejects significant amounts of oil into the intake manifold or used injectors in an uncontrolled way “pour” fuel into the cylinders.

The owner of a vehicle equipped with DPF should also remember to use low ash oils. The materials from which the particulate filters are made are sensitive to the content of sulfur, phosphorus and sulphated ashes. They form an indelible residue on the filter surface. Low-quality diesel fuel can also be a source of harmful sulfur. Let’s avoid buying fuel at points that will raise our doubts. You should also approach diesel refining additives with caution.

A clogged diesel particulate filter can be replaced with a new element (cost from PLN 700 – replacement, from several thousand zlotys – purchase of a filter at an ASO). Regeneration or chemical DPF cleaning (PLN 500-1500) or complete filter removal (PLN 800-1500) is also involved. The last solution is unlawful because the car ceases to meet the emission standards according to which it was approved.

Practice shows that cars with a cut DPF undergo technical tests without any problems. Even if the diagnostician decides to check the smoke – the permitted emission threshold is high. The consequence of removing the filter is sometimes a slight reduction in combustion and elimination of the phenomenon of oil dilution with fuel.

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