The maintenance technicians tested the 0R-3190 injectors and found that the injection timing was incorrect and the injection amount was uneven, leading to insufficient fuel combustion and excessive exhaust emissions. The reason for the abnormal injection was that the injectors were not calibrated for a long time, and the internal components were worn, leading to inaccurate injection parameters. In addition, the ECU software was outdated, which could not accurately control the injection process.