Tutorial: Diesel Particulate Filter DPF (Peugeot 407 HDI)

This article details how to fill the reservoir with additive of particulate filter (DPF on the Peugeot 407 HDI). This additive is necessary for the proper functioning of the DPF. I put first the functioning of the DPF; This will allow better understanding of maintenance related.

How does a DPF

A particulate filter (DPF) is a filter through which pass the exhaust gases. It is therefore part of the exhaust of the vehicle. It covers the Diesel engines and aims to reduce the number of harmful particles released from the exhaust. The goal is to get a less polluting vehicle.

For this purpose, the particulate filter shall proceed in 2 ways:

1. It stores the harmful particles continuously
2. it burns the stored particles from time to time

Storage of particles is simple. The exhaust gases pass through the filter. This filter has holes to allow the gas to pass, but the holes are too small to let pass the target particles. Targeted particles remain in the filter.

Problem: As all the filters, the DPF soots.

He even eventually clog quickly enough to prevent the exhaust out and severely damage the engine. The DPF system is therefore intended for to self-clean. We call this phase the "regeneration".

Regeneration: the DPF's autowash.

During regeneration, the vehicle rise in temperature the DPF, past a certain threshold, triggering the combustion of particles stored in the DPF. Once burnt, the combustion residues are small enough to pass through the filter. This cleaning is not perfect but effective enough to not to obstruct the DPF. It is clear that what comes out of the exhaust at this time is ultra toxic. Burning of toxic particles do not clean them; it only "break" them and can even produce more toxic compounds than the particles initially stopped by the filter.

To raise the temperature of the DPF, the vehicle uses several means. The engine computer inject diesel after explosion in the combustion chamber. This increases the pressure/temperature of exhaust gas which in turn heat the DPF. The vehicle can also trigger some electrical systems in order to increase electrical consumption and therefore the application applied to the alternator (ex: defrost the rear windscreen and mirrors). This over-execution is masked driver who would not understand why it is suddenly the 18L per 100km.

DPF additive: to burn less hot.

To facilitate this combustion, a system is present in order to reduce the temperature required for the combustion of particles. This system is to add diesel a component called "additive" DPF, Cerium or even by its trade name Eolys. This additive is automatically added into the tank diesel fuel. It has the particularity of not to burn in the engine and being locked in the FAP. The additive is found then mixed with also blocked particles in the DPF and has the effect of lowering the temperature necessary to trigger the combustion of particles.

I suspect that this additive has, after passage in the engine, a rather low combustion temperature. It ignites so before the particles and then heats the filter that becomes hot enough to burn the particles.

FAP additive is stored in a specific tank and is consumed as the kilometres. On 407 HDI, the 3L of additive to roll approximately 120,000 km. The car signals when the additive is too low.

Without additives, the filter is used to nothing and not long.

If you continue to ride without the brim with additive, the regeneration will no longer burn particulate matter trapped in the DPF. The filter will then become clogged and must be changed or dismantled for cleaning. This will be detected by 2 pressure sensors before and after the DPF. If the calculator sees too much pressure difference between these 2 sensors, it signals that the DPF is blocked.

The DPF in pictures

To see all of the functioning of the DPF in images, you can watch this presentation of the DPF by Peugeot Citroën (Oh no PSA has removed it from its site… congrats guys). Click everywhere for details.

Now let's see how to maintain his DPF.

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