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One of the biggest challenges in the development of a new engine and/or control system basic calibration is the construction of initial open loop maps when component characteristic curves are not available yet. It is very common in this development phase to have cylinder air charge or fuel injector terms, which effect final commanded fuel injector pulse width (i.e., injector opening time), being assigned (compensated) to wrong calibration maps as a result of the lack of reliable component characteristic curves at the beginning of calibration development. This paper presents a practical and simplified procedure for raising the basic engine maps for cylinder air mass filling, volumetric efficiency, fuel injector static flow and offset in either an engine bench or chassis dyno. This method has proven to be accurate enough to allow continuing with the basic calibration development. Comparisons to suppliers final characteristics curves show a deviation lower than 3%.

A flex fuel engine which operates with high ethanol content fuel can show a significant level of oil sump contamination with ethanol depending on startup coolant temperature and driving behavior. In general, the lower the coolant and the more aggressive the driving pattern the higher the oil sump contamination. As the engine warms up and the oil temperature increases, the liquid ethanol mixed in oil sump evaporates (boil-off phenomenon) and returns into the induction system through the engine venting system. Oil contamination and boil-off phenomena have to be properly considered by the engine management controller so that closed loop fuel control, fuel trim diagnosis and ethanol learning are not fooled by the extra fuel coming by blow-by. This paper presents the results of an analysis conducted in a GMPT 1.4L Flex Fuel engine running with E85 and E100 fuels.

Stringent vehicle emissions limits, fuel economy and driveability requirements demand an accurate air-fuel ratio management system. A flex fuel (ethanol capable) engine system without an ethanol sensor requires a precisely tuned air fuel ratio control system. In flex fuel systems without an ethanol sensor, the ethanol content is estimated based on the closed loop adaptation values, therefore; it is important to have a very good open loop estimate of cylinder trapped air and consumed fuel since an error in either of these values will cause a shift in the closed loop adaptation values and ultimately, in the estimated fuel ethanol content. This paper analyzes the effect of volumetric efficiency and stoichiometric air-fuel ratio variation of OTTO port fuel injection (PFI) engines when operating on ethanol. Proposals for correction of these parameters are compared to experimental data.