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A flex fuel engine is capable of operating efficiently on any combination of gasoline and ethanol. However, an engine combustion strategy must adapt quickly to a change in ethanol concentration after a refueling event in order to achieve optimum engine combustion. Typical control systems rely on an exhaust gas oxygen sensor (lambda) to measure changes in oxygen concentration following combustion. This feedback control approach can take five to ten minutes to detect the fuel change and correct the combustion strategy. This relatively long lag time could result in suboptimal engine performance such as a loss of engine power, engine knocking, poor cold start performance, unburned hydrocarbons, and high pollutant emissions. To counter this shortcoming, an on-board flex fuel sensor (FFS) was developed to enable a feed-forward control strategy. The FFS may be installed inline between the fuel tank and fuel injector and measure the fuel prior to it reaching the injector.

Hardware-in-the-loop (HIL) testing has become an essential verification step in the development of vehicle electronics and software systems. New system concepts continue to drive the requirements for HIL systems. The use of an open architecture for HIL testing provides many benefits to meet these requirements quickly and cost effectively. In this paper we will discuss the development of an open architecture HIL system for a J1939 bandwidth study. We will show how this HIL system was used to test and validate that a heavily loaded networks can operate without compromising the performance of safety critical systems