The paper gives a short introduction to the notion of flex fuel approach for diesel engines.
The paper continues with a description of a basic study of the diesel combustion process to allow the design of a strategy for recognition of a random bio-diesel fraction, Bx, by a purely software-based sensing technique, which creates an image of the temporal combustion behavior and uses only sensors already in service for current common rail mixture preparation systems.
A description is made of two different approaches to software- based sensing techniques, one based on the presence of a crank angle speed sensor and the other on the presence of a lambda sensor in the exhaust system. The principles of the associated software flow diagrams embedded in the engine control unit are also explained.
The paper concludes presenting a series of experimental verification data obtained on a large-scale series produced 1.3 liter turbo-charged common rail passenger car engine.