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In this study, the effect of the low octane number fuel on HCCI engine performance was experimentally investigated using a slightly modified commercial four-cylinder gasoline engine. To operate the engine in HCCI strategy with wide operational range, the blowdwon supercharging (BDSC) system proposed by the authors was applied in the test engine. Research octane number (RON) of test fuels was varied from 90 to 78.5 as an experimental parameter. Experimental results showed that in the range of the present study, HCCI operational range, brake thermal efficiency and exhaust emissions during HCCI operation were little affected by the RON of the test fuels. In contrast, during SI operation, thermal efficiency was deteriorated with lower RON fuel because of knocking.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. This report is designed to determine how high biodiesel blends affect oil quality through testing on 2005 regulations engines with DPFs. When blends of 10-20% rapeseed methyl ester (RME) with diesel fuel are employed with 10W-30 engine oil, the oil change interval is reduced to about a half due to a drop in oil pressure. The oil pressure drop occurs because of the reduced kinematic viscosity of engine oil, which resulting from dilution of poorly evaporated RME with engine oil and its accumulation, however, leading to increased wear of piston top rings and cylinder liners.

The study of 10% ethanol blended gasoline (E10 gasoline) utilization has been conducted in the Japan Auto-Oil Program (JATOP). In order to clarify the impact of E10 gasoline on vehicle performances, exhaust emissions, evaporative emissions, driveability and material compatibility have been investigated by using domestic gasoline vehicles including mini motor vehicles which are particular to Japan. The test results reveal that E10 gasoline has no impact on exhaust emissions, engine startup time and acceleration period under the hot start condition, but a slight deterioration is observed in some test cases under the cold start condition using E10 gasolines with 50% distillation temperature (T50) level set to the upper limit of Japanese Industrial Standards (JIS) K 2202. Regarding evaporative emissions, the tested vehicles shows no remarkable increase in the hot soak loss (HSL), diurnal breathing loss (DBL) and running loss (RL) testing with E10 gasolines.

JCAPII gasoline workgroup reported vehicle emission study to comprehend the impact of ETBE blending. In previous study, we focused on the compatibility of ETBE blended gasoline with Japanese current gasoline vehicles in-use. Based on recent discussion with ETBE 8% blended gasoline into the market, more information becomes necessary. In this second report, we studied to comprehend the actual emission impact using realistic model fuels using several base stocks. Fuel properties of T50, T90 and aromatic compound content were selected through discussions. Specifications were changed within the range of the market. Both ETBE 0% and 8% were combined for these fuel matrixes. In total, eight fuels and two reference fuels were tested. Two J-ULEV vehicles (one MPI, and a stoichiometric-SIDI) were procured as representatives. We discussed quantitative and qualitative impact toward emissions. Data regarding CO2 and fuel economy change were also reported.

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 effects of Injector deposits, Combustion Chamber Deposits (CCD), and Intake Valve Deposits (IVD) on exhaust emissions, fuel economy and vehicle performances have long been recognized in engine and fuel/detergent design. Because important elements of engine design such as injector position, exhaust gas recirculation (EGR) ratio, and air fuel ratio (AFR) differ from those of port fuel injection (PFI) engines, current existing test methods are not applicable. Therefore, the demand has been increasing year by year for specific evaluation methods for vehicles with direct injection spark ignition (DISI) engines which have spread rapidly worldwide. Oil and Auto Cooperation for International Standards (OACIS) of Japan selected the Mitsubishi DISI engine (4G93-1.8L) [1] and conducted engine bench tests to investigate the effects of deposits on operating conditions at 40km/h, 70km/h, 140km/h and WOT.

The effects of injector deposits, combustion chamber deposits (CCD), and intake valve deposits (IVD) on exhaust emissions, fuel economy and engine performance have long been recognized in engine and fuel/detergent design. Because important elements of the engine design such as injector position, exhaust gas recirculation (EGR) ratio, and air fuel ratio (AFR) differ from those in port fuel injection (PFI) engines, direct injection spark-ignition (DISI) engines require specific evaluation methods. However, little data is available regarding engine deposits in the more recently produced DISI engines.

The effects of engine and after-treatment control conditions on emissions fluctuation were evaluated and the technical idea for improving the repeatability in tailpipe emission measurement from DISI vehicles was provided. To improve measurement repeatability, low emissions analyzers with dilution air refining system were employed for this research. In addition, a new device that enabled monitoring of signals from the Engine Control Unit (ECU) was developed. A novel approach using these devices was applied to DISI gasoline engine vehicles equipped with de-NOx catalyst to clarify emission characteristics in the Japanese 10.15 test cycle emission tests. Through the tests, it is found that NOx emissions most correlated with the temperature at the de-NOx catalyst. CO and HC reaching the de-NOx catalyst played an important role in the temperature increase of de-NOx catalyst by exothermic reactions.

Exhaust emissions of nitrogen oxide (NOx), total hydrocarbons (THC) and carbon mono-oxide (CO) in terms of sulfur concentration were mainly investigated according to the Japanese 10.15 mode driving schedule. Tested vehicles had direct injection engines with nitrogen oxide (NOx) selective reduction catalyst or NOx storage reduction catalyst as well as stoichiometric combustion engines with three-way catalyst. Direct continuous measurement of NOx, THC and CO was also conducted. Exhaust Emissions were measured using He injection and mass spectrometry. The air fuel ratio (AFR) and driving conditions that would promote sulfur removal were found to be important factors in reducing NOx further, for recent gasoline-fueled vehicles with emerging technologies using low sulfur fuels under 100 ppm.

Evaporative emissions of Japanese older and current vehicles (1990-1998MY) and U.S. current vehicles, which were adapted to federal regulations in 1996, were investigated using typical Japanese gasoline. Japanese older and current vehicles exhibited high levels of Running Loss (RL), Hot Soak Loss (HSL) and Diurnal Breathing Loss (DBL), and their emissions showed strong Reid vapor pressure (RVP) dependence. On the other hand, U.S. vehicles showed very weak RVP dependence, between 62kPa and 76kPa. Their emissions also showed very low levels of RL, HSL and DBL. These results suggest RVP reduction is just effective for Japanese older and current vehicles. Evaporative emissions of Japanese and U.S. vehicles were also tested according to a new Japanese test procedure and the 35 degrees centigrade RL test procedure. In the case of the RL and DBL tests, the impact of test conditions on evaporative emissions was discussed as well.