In this study, the engine speed was fixed at 1200 rpm. The throttle was adjusted to be fully open, and thus engine load was
characterized by the MAP sensor. By regulating supply air, intake manifold pressures of 60 kPa and 90 kPa were used, which corresponded to engine loads of 3 bar BMEP (brake mean effective pressure) (low load) and 5 bar BMEP (high load),