Diesel-specific filters, also known as DPFs are now the method of choice for numerous manufacturers to handle soot and the ash that results from burning diesel. In essence, they function as filters in the exhaust that collects the soot and store it for later processing in the DPF burn.
We are all about performance and we are all aware that any restriction can affect the efficiency of an engine. So, what do we do about the DPF? What is it and what is the best way to treat it?
The DPF can be deleted out of the exhaust and software. This is the simple solution to the problems caused by having the DPF. I’m not going to go into all the legal stuff of removing an emission-related device. I’m simply saying this is the best solution.
One benefit of a DPF is that it reduces the amount of soot released into the air. One might say it is a benefit for the environment. However, that’s a general assertion at best. It is necessary that a DPF regenerate or burn off the soot regularly. How to do this is by making the DPF hot enough to burn off the soot and ensure it can flow through the filter. Another way to achieve this is when the ECU injects fuel, in addition, to creating additional warmth in the filter for burning off. In this way, it consumes more fuel (not eco-friendly) Additionally, a portion of this fuel is absorbed into the sump of the engine, reducing the engine oil, which could result in additional oil and filter changes.
Similar to when catalytic converters when were installed and lead was removed from fuel due to the fact that it could harm the converter. Cars with dpf gaskets require specific oils that are low in sulfate ash, as well as phosphorus and sulfur (low saps). If the oil is not properly used, it will block the DPF and prevent its regeneration. This makes it necessary to replace DPF. One downside of DPF is its cost to replace it.
Some believe that the oil requirement of the DPF results in internal wear rates for the engine than if normal oil was used. We’ll debate this another day.
The most common issue we encounter the most with DPFs is the case of a boost leak. The leak can result in an increase in soot and smoke within the exhaust system and will block the DPF pretty quickly. After the leak has been repaired, a DPF clean will almost always be necessary. We can do a DPF clean even with the DPF still mounted to the vehicle. After the DPF clean has been completed Regens can take place. When it’s necessary to conduct a regen that is forced, the engine oil is required after the regen. How do you know? When extra fuel is injected to get the DPF heated enough to make it suitable for regening the engine, this fuel is going to reduce the strength of the engine oil.
So what is a forced regen anyway? The process of forcing a regen involves using a scan tool to initiate a burning while you are stationary. In most cases, a forced burn will employ a higher temperature, and the regen tool will be monitoring the pressures in the DPF as it goes through the process. Specific tools are needed to conduct a forced re-generation so your average mechanic may not be able this. But be aware you don’t need to use a dealer. We prefer a range of equipped workshops that have the devices to do a forced regen.
In more extreme cases a forced regen will not be possible due to the extent of soot loaded. The next step of the process is an on-car clean. The tool for cleaning your car is a two-step process. The cleaner is injected into the DPF and then processes the soot within a specific period. The cleaner is then purged from the system which leaves the DPF prepared for a regen. The on-car cleaning equipment is much less common for workshops to possess. We are also able to assist with on-car DPF cleaning.
This is just an overview of the DPF and some of the advantages and disadvantages associated with its usage.