There is a lot of misinformation being spread about cleaning diesel particulate filters (DPFs). We have heard everything from active and passive regeneration being enough to people resorting to deleting the DPF system completely. However, are you aware single truck owners can be fined $2,500 per incident? And large truck companies might have to part with hundreds of thousands of Dollars or more for tampering with or deleting these systems.
Passive DPF Regeneration
Quite simply, this is the cleaning that occurs automatically when trucks are running at speed, typically on the highway. In this situation, the exhaust is typically hot enough to burn off the soot that can clog a filter. This cleaning tends to become less effective when a truck is stuck in stop and go traffic or operation that does not allow the truck to get up to full operating temperature for extended periods.
Active DPF Regeneration
Active regeneration is used to manually increase the exhaust temperature in an attempt to burn off the soot. This is typically initiated by the operator of the vehicle. Essentially, the vehicle ECU initiates a specific fuel injection process designed to increase the exhaust temperature reaching the DPF to over 600 °C in an effort to stimulate oxidation of the particulate deposits in the filter.
DPF Out Cleaning
Even with passive and active DPF regeneration, you will occasionally need to remove the DPF from the vehicle for a more extensive cleaning. You might notice that the truck needs more passive and active regenerations to continue running properly. You might also notice decreased performance or a lower fuel economy. These are indications you need to have a DPF out cleaning done.
This process will keep the vehicle operating as designed and help you avoid a costly DPF replacement if the vehicle continues to operate with a clogged filter. A diesel mechanic will remove the filter and take it through a very thorough cleaning process with DPF cleaning equipment designed for this process. This is typically done by heating the filter to loosen the particulate and then using either forced air or fluid to remove the soot from within the filter.
This article was originally published by IDEA member Enviromotive (Anaheim, California)