Diesel Particulate Filter - Matter

What is Diesel Particulate Matter DPM?

Diesel Particulate Matter (DPM) is un-burnt fuel that is released into the exhaust. This component of diesel exhaust (DE) includes soot particles made up primarily of carbon, ash, metallic abrasion particles, sulfates and silicates. Fact: most diesel engines only burn an average 50-55% of the fuel injected into them. As a solution to reducing the DPM the DPF or Diesel Particulate Filter was introduced and was required to added to all diesel engines in 2007.


What is a Diesel Particulate Filter DPF?                                                                                                                                 

A diesel particulate filter (or DPF) is a device designed to remove/trap diesel particulate matter or soot from the exhaust gas of a diesel engine. Overtime the trapped soot builds up inside the filter and clogs it. There are three types of diesel regeneration.

1. Passive regeneration takes place automatically on motorway or fast road runs when the exhaust temperature is high. Because many cars don't get this sort of use vehicle manufacturers have had to design-in 'active' regeneration where the engine management computer (ECU) takes control of the process.

2. Active regeneration is when the soot loading in the filter reaches a set limit (about 45%) the vehicle's ECU will initiate post combustion fuel injection (wasted fuel) to increase the exhaust temperature and trigger regeneration. If the journey is too short while the regeneration is in progress, it may not complete and the warning light will come on to show that the filter is partially blocked. This can lead to the DPF getting clogged and needing cleaning or a very expensive replacement.

3. Some newer diesel engines, namely those installed in combination vehicles can also perform what is called a Parked Regeneration, where the engine increases RPM to around 1400-1700 while parked, to increase the temperature of the exhaust and clean the DPF. Warning, do not stop the regeneration cycle.

A DPF was designed for long life, eventually the accumulated ash must be removed by special cleaning equipment. The typical cycle for the DPF before it needs to be cleaned varies by the use of a vehicle. Idling or stop and go driving may require monthly maintenance, in over the road driving manufacturer estimates range from 100,000 to 150,000 miles. On vehicles that do a lot of stop-and-go driving (school busess, coach buses, gargage trucks, ambulances, fire engines, etc.) maintenance and replacement may be required monthly or quarterly. Every engine is different even if it is made by the same manufacturer.

One thing’s for sure: replacing the DPF is not cheap (+/-$3,500 or more plus installation) and could result in performance problems and cost issues incurred by downtime for the repair.

How can a diesel engine owner reduce DPF maintenance?

1. Fuel; use a low sulfur diesel fuel. (bad fuel more soot)
2. Use CJ-4 oil (DEF Diesel Emission Fluid) that was designed for 2007 and newer diesel engines with a DPF. Using older CI-4 oil may contribute to the clogging of the DPF and may void an engines warranty. Change Oil change intervals should be done as recommended. The dirtier the fuel the more DEF used.
3. The ECO Fuel System is a preferred low cost (+/- $400) patented and proven inline fuel vaporizer that can reduce Regeneration Cycles and soot build up. It works by reducing the size of the Hydrocarbon molecules in fuel increasing the Reid Vapor Pressure causing the fuel to burn more volatile and cleaner. A Cleaner burning fuel results in less soot and improved efficiency. (SGS report)

Cleaning a DPF is a required part of periodic maintenance and it must be done carefully to avoid damaging the filter. Conventional cleaning is done by placing a DPF into an oven at +/- 3,000 degrees Fahrenheit to loosen and remove the soot. Approximately 20% of the DPF efficiency is lost after a cleaning. Other lower cost Biodegradable solutions like Cobra Clean are also available. Failure of fuel injectors or turbochargers resulting in contamination of the filter with raw diesel or engine oil can also necessitate cleaning. The regeneration cleaning process occurs at road speeds higher than can generally be attained on city streets; vehicles driven exclusively at low speeds in urban traffic can require periodic trips at higher speeds to clean out the DPF. If this is not done the DPF filter will clog and may require an expensive repair and downtime.

If the driver ignores the warning light and waits too long to operate the vehicle above 40 miles per hour (64 km/h), the DPF may not regenerate properly, and continued operation past that point may spoil the DPF completely, it must be replaced.  

What is Diesel Regeneration?