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In response to industry demands for a method to qualify fuels for their intake valve deposit (IVD) forming tendencies, the Coordinating Research Council (CRC) has developed an engine dynamometer test procedure. In Phase I, the 2.3L Ford engine was chosen as the focus test engine in comparison testing with two other high volume U.S. manufactured engines.1* A two-mode dynamometer test was developed in Phases II-A & II-B and shown to discriminate among the test fuels at a 95% confidence level.2 In Phase III, both an interlaboratory study (ILS) of the two-mode dynamometer test and a vehicle fleet study were performed. The ILS was conducted to determine the repeatability and reproducibility of the test procedure and also to fulfill requirements for consideration of the test as an American Society for Testing and Materials (ASTM) standard.

The 1991 Ford 2.3L engine was selected as a test engine for purposes of developing a standard industry accepted intake valve deposit test. Candidate engine selection criteria and test protocol are discussed. Three 1991 domestic engine types were compared for intake valve deposit (IVD) characteristics using the SwRI/BMW on-road cycle. A composite blend of six, non-additized fuels was chosen for both base fuel and base fuel + additized tests. A test matrix was designed to assess both IVD accumulation characteristics and sensitivity to additive chemistry for each engine. Screening tests were performed using two 1985 BMW 318i sedans to find a suitable additive for additized tests and to use as a reference to the existing database.