New developments of the 3 ^rd generation SFS-Flex system to meet PL5/6 emission requirements.

The paper presents a short introduction on the evolution from the first generation of software based flex fuel sensor systems over the second system generation including new gasoline/ethanol optimized fuel injectors to the 3^rd generation, which combines all available optimized mechanical components.

It demonstrates that to meet the new emission regulations and On Board Diagnostic requirements a new highly flexible Electronic Control Unit (ECU) is needed. A detailed description of the new powerful, layered-structure ECU-family is given.

The paper concludes with some illustrative experimental results obtained by combining the new ECU-family with engine-layout optimized mechanical components.