Effects of a B70 biodiesel blend on the ECU and fuel system operation during steady-state and transient performance of a common rail diesel engine

Abstract

The results of steady state and transient engine bench tests of a 2.0 l common-rail passenger car diesel engine fuelled by B70 biodiesel blend are compared with the corresponding results of baseline tests with standard EN 590 diesel fuel. The macroscopic steady-state performance and emissions of the same engine has already been presented elsewhere. The aim of the current study is to demonstrate how the engine's electronic control unit (ECU) and fuel system responds to different fuel properties, with emphasis to the fuel system dynamics and the engine's transient response. A series of characteristic transient operation points was selected for the tests. Data acquisition of all monitored engine ECU variables was made by means of INCA software/ETAS Mac2 interface. Additional data acquisition regarding engine performance was based on external sensors. The results indicate significant differences in fuel system dynamics and transient engine operation with the B70 blend at high fuel flow rates. Certain modifications to engine ECU maps and control parameters are proposed and discussed, aimed at improvement of transient performance of modern engines run on high percentage biodiesel blends. However, a high pressure pump failure that was observed after prolonged operation with the B70 blend, hints to the use of more conservative biodiesel blending in fuel that should not exceed 30%.