The speed and torque of each test point in the WHSC test cycle are shown in fig4 . The number in the circle represents the test sequence in the WHSC test cycle. The same injection strategy as the original engine was employed under both cold and warm idle conditions to obtain better combustion stability and cold-start performance. The other eleven test conditions were all using single injection strategy with injection pressure of 160 MPa. The earliest injection timing was restricted by the maximum pressure rise rate or the maximum cylinder pressure. The combustion and emission characteristics of the tested fuels were compared at five different weighted NOx targets, which were achieved by varying the EGR ratio.