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. The CCD test was defined as a 50-hour two-mode cycle, which includes 25 hours at 1900 rpm and 43.5 N-m load (70 km/h road load) and 25 hours at 1300 rpm and 23.6 N-m load (40 km/h road load). This test cycle was selected from among five candidate test procedures and is based on the Japanese 10-15 mode. Detergent additives such as polybutene amine (PBA) additive and polyether amine (PEA) additive were used for the test.The study is part of the overall effort toward increased standardization, and this CCD test procedure is scheduled to be standardized as a Japanese Automobile Standard Organization (JASO) test in 1998.