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LEV-3 regulation changes require 100% SULEV30 fleet average by 2025. While present applications meeting SULEV30 are predominately small displacement 4-cylinder engines, LEV-3 standards will require larger displacement engines to also meet SULEV30. One concept previously investigated to reduce the cold start engine-out HC emissions was to heat the fuel injected during the cold start and initial engine idle period. Improved atomization and increased vaporization of heated fuel decreased wall wetting and unburned fuel. This resulted in more fuel available to take part in combustion, thus reducing the required injected fuel mass and HC emissions. Single cylinder engine testing with experimental heated Gasoline Direct Injection (GDi) injectors was conducted at 40°C engine coolant and oil temperature conditions. The operating mode simulated cold start idle operating conditions, with split injection for improved Catalyst Light-Off (CATLO) times.

Gasoline direct injection provides reduced engine emissions, increased power, and increased fuel economy as compared to port fuel injection (PFI). Reduced emissions are largely due to starting the engine using high fuel pressure (up to 150 bar) and injecting into the compression stroke. During a cold start, fuel pressure must be increased from lift pump pressure (typically 4 to 6 bar) to desired injection pressure (typically 25 bar minimum). Start times are therefore impacted by the high pressure pump's ability to quickly build fuel pressure during crank. This study investigates the temperature and pressure affects during engine soak which allow vapor and air to form in the fuel system. Vapor and/or air in the system cause a slower fuel pressure build and increases start times. The scope of the problem and possible solutions were determined using theoretical and empirical testing.

Fuel injectors capable of rapidly electrically heating ethanol for cold starts below ethanol's flash point temperature have been developed for the Brazilian transportation market. These injectors also enable the enleanment of 20°C cold start fueling, which has shown to reduce FTP bag emissions. Initial E-100 vehicular emission test results were published in SAE paper 2009-01-0615 and presented during the 2009 SAE Congress. Further development has shown that heated injector systems can enable emission reductions with a variety of automotive fuels. Engine control strategies which make use of heated injector systems, along with corresponding test results, are presented and discussed.