To investigate the effect of split injection on exhaust emissions, soot particulates, and engine performance, experimental investigations were conducted using an electrically controlled direct-injection diesel engine fueled with neat biodiesel derived from soybean. Split injection, with varied injection timing, was investigated, and the results were compared to those obtained by single injection. The experiments were conducted under a fixed engine load condition and a constant dwell time between the first and second injections. The results show that split injection reduces NO, emissions significantly without a significant increase in soot emissions. A markedly different tendency was found when injection timing was retarded for single and split injection cases. In the case of single injection, increasing soot, median particle diameter, and particle number concentration were seen in accordance with retarded injection timing. However, the reverse tendency was found for split injection.