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The use of a diesel particulate filter (DPF) is one of the most flexible methods of reducing particulate emissions from diesel engines, and has the advantage of controlling both the number and mass of particulate emissions. To maintain engine performance over time, the soot accumulated in the filter needs to be removed by oxidation. This paper describes the development of a novel iron based fuel-borne additive that controls soot deposit build-up in DPFs. This technology controls soot accumulation at significantly lower treat rates than those of previously reported [1] additives at temperatures well below those previously required for soot combustion. Ash accumulation testing and the chemical characterisation of the ash are also described. Any successful solution to the problem of soot accumulation in the filter needs to be harm free in the field.

The high frequency reciprocating rig (HFRR) was developed in the early 1990s as a test method to assess diesel fuel lubricity in order to provide wear protection for fuel injection pumps. This was necessary in response to the many field failures that occurred following the introduction of ultra-low sulphur diesel in Sweden. The prevalent fuel injection equipment (FIE) technology at this time utilised rotary pumps capable of reaching maximum fuel pressures of ∼650 bar in systems for direct injection engines. The continued drive for efficiency led to many changes in FIE technologies, materials and pressures. Modern high pressure common rail pumps reach significantly higher pressures, with 2200 bar available today and pressures up to 3000 bar discussed in the industry.

Internal Diesel Injector Deposits (IDIDs) have been known for some time. With the latest powertrains becoming ever more sophisticated and reliant on efficient fuel delivery, the necessity for a continued focus on limiting their formation remains. Initial studies probed both carbonaceous based/ashless polymeric and sodium salt based IDIDs. The reported occurrence of the latter variety of IDID has declined in recent years as a result of the removal of certain additives from the diesel distribution system. Conversely, ashless polymeric based deposits remain problematic and a regular occurrence in the field.

The use of Diesel Particulate Filters (DPFs) as a means to meet ever more stringent worldwide Particulate Matter/ Particle Number (PM/ PN) emissions regulations is increasing. Fuel Borne Catalyst (FBC) technology has now been successfully used as an effective system for DPF regeneration in factory and service fill as well as retrofit applications for several years. The use of such a technology dictates that it be stable in long term service and that it remains compatible with new and emerging diesel fuel grades. In order to ensure this, neat additive stability data have been generated in a very severe and highly transient temperature cycle and a large selection of current (Winter 2012) market fuels have been evaluated for stability with this FBC technology. Results indicate that FBC technology remains suitable. The incidence of Internal Diesel Injector Deposits (IDIDs) is increasing, particularly for advanced FIE systems.