DPF stands for diesel particulate filter. These filters are used to minimize the number of hazardous particulates that are emitted from combustion systems in diesel vehicles. Its goal is to make the surrounding air cleaner and safer, especially in tight spaces. EHC Teknik produces DPF filters to suit various needs, and we’re happy to address any questions you have about this technology. Read on to find out more.
Euro 5 standards
Since 2009, when the “Euro 5′ standard took effect, exhaust emission standards for diesel vehicles have effectively required the fitment of a DPF in the exhaust systems. In actuality, the majority of vehicles that were built before 2009 will come with an exhaust filter installed as well.
They are also justified due to the fact that diesel particulate (soot) emissions cause serious health issues in humans. DPFs lower the emission of diesel smoke by 80% but they’re not appropriate for all. Even if your driving style is not mainly urban/stop-start, changes to your driving habits may be necessary for these systems to function efficiently.
What is the process by which diesel particulate filters operate?
Diesel Particulate Filters (DPF) catch soot particles and prevent them from exiting out of the exhaust. As with any filter that is used, they need to be cleaned frequently to ensure their performance. For a DPF this is known as ‘regeneration’. This process involves the collected soot being burned off at high temperatures so that there is only ash.
Regeneration can be either passive or active
Passive regeneration
Passive regeneration takes place automatically in the motorway whenever the exhaust temperature is high. Since many cars aren’t driven on the motorway very frequently, car manufacturers have created “active” regeneration. This is where an engine control computer (ECU) controls the process.
Active regeneration
When the filter is clogged up with soot to the set amount (about 45percent) then the car’s ECU will begin post-combustion fuel injection to increase the exhaust temperature and trigger regeneration. If the motor is shut off while the regeneration process is going on, it might not be complete and the warning light will flash on to indicate that the filter is partially blocked.
It is possible to complete a cycle of regeneration and remove the warning light by driving, and then increasing the temperature as a result.
Effects of active regenerative
In active regeneration, you may have the following symptoms:
- Cooling fans running
- Increased idle speed
- The deactivation of automatic Stop/Start
- A slight increase in the consumption of fuel
- A hot, acrid smell from the exhaust.
- Engine note changes
If the regeneration fails due to an inadequate running cycle, the extra fuel that is injected into the cylinders will not burn and will drain into the sump. The quality of the oil will decrease and the level of oil will increase. The majority of DPF-equipped engines will have an oil quality/viscosity gauge, however, it is important that you be sure the oil level doesn’t exceed the level that is indicated on the dipstick as diesel engines operate using their own oil in the event that the level is high, frequently to the point of destruction.
If you disregard the warning signal and continue driving in a fairly slow, stop/start pattern, soot will continue to build up to around 75% by the time you should expect to see additional dashboard warning lights turn on. At this point driving at a steady speed won’t suffice to remove the filter. You’ll require taking the car to a repair shop to undergo “forced” regeneration.
Forced regeneration
Regeneration by force is mandatory when “active” regeneration criteria have not been met, and soot levels within the DPF have increased by about 70 percent. If left unattended, the load of soot will continue. At this level, an instrument for diagnostics must be employed to initiate regeneration. At around 85% soot loading, regeneration can no longer be achieved on the vehicle. In this case, you will need to get rid of the DPF to be replaced or cleaned.