In this experimental investigation, the combined effects of engine parameters on the performance and emission characteristics of a single cylinder, direct injection(DI) diesel engine, fueled with an upgraded Jatropha Methyl Ester (JME) – Wood Pyrolysis Oil (WPO) emulsion which is referred to as ATJOE15, were studied. The ATJOE15 comprises of 15% WPO and 81% JME and 4% surfactant. Experiments were conducted at three different injection timings viz., 21.5, 23 and 24.5oCA bTDC, and three nozzle opening pressures viz. 200, 220 and 240 bar while the standard compression ratio of 17.5 is maintained during this study. At the standard compression ratio of 17.5 and at standard injection timing, with the higher nozzle opening pressures of 220 bar and 240 bar, the brake thermal efficiency of the ATJOE15 emulsion is found to be higher than that of diesel by about 4.6% and 6.1% respectively at full load. With the retarded injection timing of 21.5 oCA, the NO emissions of the ATJOE15 emulsion are found to be lower by about 12.8%, compared to that of diesel operation at standard nozzle opening pressure of 200 bar.