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A program with title of “Development of automobile and fuel technologies for air quality improvement (Japan Clean Air Program - abbreviated to JCAP) has been conducted as a five-year program. Under the program, an influence of fuel quality on automobile technology has been evaluated, and effect of air quality improvement due to implementation of automobile exhaust emission regulations has also been evaluated by using air quality models. Through the five years of JCAP activities from FY 1997 to FY 2001, following items have been evaluated: an influence of fuel properties and automobile exhaust emission reduction technologies, an evaluation of aftertreatment devices equipped on in-use vehicles, a detailed analysis of fuel properties and exhaust emissions, a prediction of air quality improvement effects due to the implementation of next stage stringent automobile exhaust emission regulations.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

Worldwide concern about combustion chamber deposits (CCDs) has increased from the viewpoint of fuel and additives technology, which has been developed for the cleaning of intake valve deposits (IVDs), intake port deposits and injector deposits. The research effort described here, focused on the differences between CCDs and IVDs in terms of quality based on analyses of CCDs and IVDs collected from used vehicles from the Japanese market. The CCDs and IVDs were characterized according to weight, benzene-solubles and sulfated ash. Since the sulfated ash in CCDs is a key to understanding the effect of engine oil on CCD formation, the relationship between CCDs and the sulfated ash in CCDs was evaluated under the two typical conditions on a 2.0L engine testing bench. Based on the results, the gasoline-related and oil-related factors were estimated for these conditions. Moreover, the effect of CCDs on exhaust emissions was investigated in a 2.2L vehicle.

The effects of gasoline volatility (T50 and T90), sulfur content and hydrocarbon types on CO, NOx, total hydrocarbon and speciated hydrocarbons were investigated. The properties of the test gasoline were varied in the range of the Japanese marketplace gasoline, which are characterized by low T50, T90 and low sulfur content. Sulfur content is, especially, regulated under 100 ppm. The Japanese 10.15 mode emissions under hot-transient conditions were measured by using a vehicle equipped with a three-way catalyst. The results indicated that the sulfur content was more effective on exhaust CO, total hydrocarbon and NOx emissions than T50, T90 or hydrocarbon types of gasoline were. The sensitivity to sulfur was different depending on the speciated hydrocarbons. Increasing the sulfur content significantly raised exhaust paraffines, but had no significant effect on olefins. Among the aromatics, the exhaust benzene was most sensitive to sulfur.

To reduce engine exhaust emissions, we have had to deal with this global environmental problem from the fuel side by introducing oxygenated fuels, reducing the RVP and using low aromatics. But when we change the fuel components and distillation, we must take note about how these affect the engine driveability. We have used T50, T90, RVP and so on as the fuel index up to the present. It is possible to characterize the fuel from one aspect, but these indexes don't always represent the real feature of the fuel. In this paper we propose a New Driveability Index (here in after referred to as NDI) that is more realistic and accurate than the other fuel indexes. We used a 1600cc DOHC L4 MPI type engine. We used Model Gasolines and Market Gasolines, see Appendix(1), (2) and (3), and tested them according to the Excess Air Ratio Response Test Method (here in after referred to as λ-R Test) that was suggested in SAE paper #930375, and we calculated the NDI statistically.

Recently, an audible clattering noise has been noticed in some vehicles during cold engine starts, mainly in the U.S. The clattering is referred to by various names, such as “carbon knock,” “carbon rap,” “mechanical knock” and “combustion chamber deposit interference (CCDI).” CCDI is believed to be caused by the deposit formation in the combustion chamber. In the research effort described here, CCDI was successfully reproduced in a 2.5-liter multipoint injection engine with a polyolefin amine gasoline additive. It was determined that the CCDI was caused by mechanical contact between the piston top and the cylinder head deposits. The vibration due to CCDI originated mainly at the thrust side of the piston right after top-dead-center on compression stroke and was characterized by a high frequency response. Combustion chamber deposit (CCD) formation depends on many factors, including gasoline additives.