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Clarifying the impact of ETBE 8% blended fuel on current Japanese gasoline vehicles, under the Japan Clean Air Program II (JCAPII) we conducted exhaust emission tests, evaporative emission tests, durability tests on the exhaust after-treatment system, cold starting tests, and material immersion tests. ETBE 17% blended fuel was also investigated as a reference. The regulated exhaust emissions (CO, HC, and NOx) didn't increase with any increase of ETBE content in the fuel. In durability tests, no noticeable increase of exhaust emission after 40,000km was observed. In evaporative emissions tests, HSL (Hot Soak Loss) and DBL (Diurnal Breathing Loss) didn't increase. In cold starting tests, duration of cranking using ETBE 8% fuel was similar to that of ETBE 0%. In the material immersion tests, no influence of ETBE on these material properties was observed.

The authors developed a direct injection stratified charge engine employing a center-injection system in which a high-pressure fuel injector is located in the center of the combustion chamber and the fuel spray is vertically injected into the cylinder toward the piston bowl. Stratification is controlled by the fuel spray characteristics and the piston-bowl shape which were calibrated using CFD simulations and in-cylinder analyses. The VTEC mechanism is employed to control the burn rate with in-cylinder swirl gas motion, which is generated by one-intake-valve deactivation. Optimization of the mixture preparation and combustion through calibrations of the piston bowl, the fuel spray characteristics of the high pressure injector and the in-cylinder gas motion enabled stable combustion with an ultra lean air-fuel ratio of 65. As a result, this engine has significantly improved fuel economy and emissions.

The purpose of this paper is to quantify the improvements possible for ULEV emissions by improved air-fuel ratio control during starting by modifying conventional fuel injection strategy with a first order wall-wetting-fuel model. Measurements of emissions during first 30 starting cycles of a ULEV engine, made with a fast response flame ionization detector (FID) and conventional fuel injection strategy, show that these account for 17% of the overall FTP-75 mode HC emissions. The wall-wetting-fuel model is a two coefficient model: α, the ratio of the injected fuel mass to the fuel mass inducted into the cylinder during a given cycle, and β, the ratio of the total fuel mass accumulated on the intake port wall to the mass inducted into the cylinder from the accumulated fuel at a given cycle.

The reduction of fuel consumption is of great importance to automobile manufacturers. As a prospective means to achieve fuel economy, lean burn is being investigated at various research organizations and automobile manufacturers and a number of studies on lean-burn technology have been reported to this date. This paper describes the development of a four-valve lean-burn engine; especially the improvement of the combustion, the development of an engine management system, and the achievement of vehicle test results. Major themes discussed in this paper are (1) the improvement of brake-specific fuel consumption under partial load conditions and the achievement of high output power by adopting an optimized swirl ratio and a variable-swirl system with a specially designed variable valve timing and lift mechanism, (2) the development of an air-fuel ratio control system, (3) the improvement of fuel economy as a vehicle and (4) an approach to satisfy the NOx emission standard.