Tuesday, 16 August 2016

The required and correct maintenance of the particulate filter (FAP)

In 2010, the Euro 5 standard came into force that requires car manufacturers to install a Particulate filter (DPF or FAP), among other elements, in the exhaust systems of diesel engines.
The purpose of the FAP is to store soot particulates generated by the incomplete combustion of the fuel, which drastically reduces the harmful particulate levels emitted to the atmosphere.

The FAP is a particularly effective mechanical filter which is made up of honeycomb type cells that trap the particulates emitted during combustion. It can retain more than 99% of the combustion particulates.

Particulate filter

To regenerate the Particulate Filter and prevent internal saturation with soot, the system carries out a regeneration process. This process is activated when certain technical temperature and running conditions are fulfilled. When these conditions are met, the engine control unit starts this process by acting on the injection system in order to raise the temperature inside the particulate filter, and thus burn the soot accumulated in it.

Unfortunately, many current running conditions (short journeys, cold engine, etc.) do not allow an adequate regeneration, in other cases the regeneration starts but never finishes because the user stops the vehicle before the process has completed. In these cases, the filter will still have stored particulates, which saturate it and reduce its useful life.
Once the saturation limit is exceeded, a warning of type "Defective emissions control system" is sent to the driver and the corresponding warning light on the instrument panel is switched on, and it will go to degraded mode (after a running time), which means the driver must make a visit to the garage for its repair.

In these circumstances, certain actions are required. Depending on the vehicle and the degree of obstruction of the FAP, there are various options for its correct recovery:

A) A forced regeneration using the diagnostic machine (a procedure which has limitations)
B) A forced regeneration by means of a diagnostic machine and the application of a chemical deposition product that acts by reducing the combustion temperature of the soot. This procedure results in a substantial improvement in the removal of particulates from the FAP. Once the forced regeneration is complete, it is recommended to take the vehicle on the road to optimise the removal of residues from inside the exhaust system.
C) Introduce specific chemical products for this function inside the FAP through the differential pressure sensor pipes or into the particulate filter depending on the vehicle's set-up. The chemical product will dissolve the soot which will be finally removed by applying a type B regeneration.
D) Remove the FAP, carry out a direct mechanical cleaning or replace it with a new one.

After the recovery of a FAP, it is important to carry out intensive preventive maintenance, that is, an enhanced regeneration must be carried out using a chemical product at least once a year.

To avoid stressing the mechanics of the vehicle, it is highly recommended to work with chemical products that reduce the destruction temperature of the soot. This service should be carried out by the mechanic using the diagnostic machine or going out on the road for optimal regeneration.
To ensure the particulate filter is well maintained, the mechanic should ask the customer about the type of driving or use that is made of the vehicle, and thus advise him or her on the most appropriate maintenance to prolong the life of the FAP and reduce the risk of major repairs.
For those vehicles that, due to the way they are used, are considered at high risk from premature saturation of the FAP, it is recommended to advise the customer that they carry out a type B regeneration maintenance procedure at each oil change.

For your information, there are specific products on the market for the regeneration of the FAP (that also provide additional benefits to other elements exposed to the exhaust gas such as the turbocharger, EGR valve, catalytic converter, etc.) To know more about these products click here These articles are available through the AD distribution network.

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