Development of an Intake Valve Deposit Test with a GM LE9 2.4L Engine

The U.S. Environmental Protection Agency (EPA) certifies gasoline deposit control additives for intake valve deposit (IVD) control by means of ASTM D5500, a vehicle test using a1985 BMW 318i vehicle equipped with a 1.8L I-4 port fuel injected engine. Concerns with the age of the test fleet, its relevance in the market today, and the availability of replacement parts led the American Chemistry Council’s (ACC) Fuel Additive Task Group (FATG) to begin a program to develop a replacement test. General Motors suggested developing a replacement test using a 2.4L LE9 test engine mounted on a dynamometer and committed to support the engine until 2030. Southwest Research Institute (SwRI®) was contracted to run the development program in four Phases. In Phase I, the engine test stand was configured and a test fuel was selected. In Phase II, a series of tests were run to identify a cycle that would build an acceptable level of deposits on un-additized base fuel. In Phase III, the resultant test cycle was examined for repeatability. In Phases IVa and IVb, two discrimination matrices evaluated the response of additives on IVD levels. The results of Phase IVa indicated the EPA 65th percentile fuel and test procedure combination did not compare with historical BMW vehicle results or replicate the BMW additive discrimination. Phase IVb, using a TOP TIER™ certification fuel, did show a representative additive response in the LE9. FATG considers the initial test development complete, but continued evaluation of the fuel, hardware, and test cycle will be required. With continued development in a future Coordinating Research Council (CRC) program, ACC FATG anticipates that the GM LE9 2.4L IVD test, designated the “2.4L IVD test” in this document, can be standardized as an ASTM test method, and used as an alternate or replacement for the ASTM D5500 in both EPA and California Air Resources Board (CARB) Reformulated Gasoline regulations. This would also position the 2.4L IVD test to become a replacement for the ASTM D6201 IVD test.