Souza, R., Carvalho, C., and Bertolucci, R., "Turbocharged Flex Fuel Vehicles with Virtual Ethanol Content Identification," SAE Technical Paper 2017-36-0241, 2017.
The identification of fuel blends using software strategies and the oxygen sensor are widely known for flex fuel and naturally aspirated engines in Brazil, since its first launch in 2003. It represents a cost effective alternative to identify the ethanol content in the fuel, which is being used in the combustion, with an accurate performance and reduced complexity. With the introduction of flex fuel vehicles equipped with turbocharger, especially the ones with Direct Injection (DI) technology, an ethanol sensor as an additional product has been used so far to identify the ethanol content in the fuel blend. Such engine types may be more sensitive to fuel mixture deviations, since it works with higher loads, more combustion chamber pressure and an extended temperature range in comparison with the normally aspirated applications. Due to these reasons, worst-case scenarios with high ethanol content deviation could cause damage to the engine and exhaust hardware. This paper aims to analyze the challenges of different system architectures and to present the results of adopting a fuel blend identification strategy in a flex fuel turbocharged engine without an ethanol sensor, such as its accuracy and performance.