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Heavy duty diesel engine development has always faced high customer durability requirements, short development timelines and increasingly stringent emissions legislations. However, more frequently heavy duty engines are being used in multiple vehicle platforms across the globe with increasingly stringent quality demands in emerging markets. In order to meet engine life requirements, Delphi Diesel Systems has adapted accepted validation procedures to evaluate their system performance for the global market. In addition to durability and structural testing Delphi Diesel Systems has introduced specialized tests to validate their product at extremes of environmental conditions and fuel properties and has increased OEM collaboration. This paper details some of the adjustments made to the validation test suite to meet the specific challenges of the Heavy Duty market.

Internal deposits formed within the fuel injection system have been widely reported in the literature. Several root causes exist, with many deposits consisting of more than one material. The final chemistry depends on the availability of trace fuel contaminants and additives and to a lesser extent hydrocarbon/FAME stability and operating conditions. The present paper identifies the primary deposit morphologies, along with the typical root cause. Metal carboxylate salts, also known as metal soaps are most widely reported and are easily recreated under controlled conditions using compounds present at trace concentrations in some market fuels. The salting reaction may occur at low temperatures in the fuel supply system. It is proposed that the resulting fuel insoluble salt molecules are transported as reverse micelles, occasionally plugging filters but more commonly passing to the high pressure injection system.