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Diesel engines will require new hardware to meet future emissions levels required by upcoming legislation. One of the key enablers towards meeting such legislation is the use of better fuel injection equipment (FIE). However, these systems can produce temperatures at the injector tips that are considerably higher than those seen today. This environment can exacerbate the rate of deposit formation or generate new types of deposits at and around the injector tip. Previous and ongoing investigations continue to further our understanding of this phenomenon using a modern passenger car diesel engine, various commercial 10 ppm S diesel fuels, a severe test cycle and injector nozzles representative of those likely to be in use in EURO V engines. The engine tests show good repeatability with clear and treated fuels. This supports the validity of the data generated. The test protocol used has recently been released to the industry.

Continued legislative pressure to reduce diesel emissions has resulted in the development of engines with advanced fuel injection equipment (FIE). These injection systems produce temperatures and pressures at the injector tips that are considerably higher than those seen in previous technologies. This environment is initiating deposit formation at and around the injector tip which is leading to significant power loss and increased smoke generation. Investigations have been carried out to understand this phenomenon. Cyclic bench engine testing has generated high levels of deposits when minimal amounts of a fuel soluble zinc salt are doped into clear fuels. The deposits are found both in and around the nozzle tips. Analysis of the deposit shows the presence of zinc. These deposits are proving to be more challenging than those previously seen with older FIE technology. Detergents that have historically been effective in resolving injector deposits are proving less effective.

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.