An internal combustion engine that uses fixed injection timing and rates often suffers from low performance and increased emissions, which can occur due to variations in load and speed. Bosch’s electronically controlled unit injectors (EUIs) address these challenges by combining the functions of the fuel pump and injector into a single unit. This system employs common rail technology, enabling precise electronic control over the timing, quantity, rail pressure, and the number of fuel injection pulses. Consequently, this technology enhances engine performance, improves fuel efficiency, and reduces emissions. In this study, we developed a simulation model that incorporates details of the Bosch injector and the common rail system, utilizing GT-Power commercial software. In the model, diesel fuel is injected in two modes: single pulse injection and multiple pulses injection (pre- and main pulses), aimed at optimizing the combustion process. For multi-pulse injection, both pulses are electronically controlled by the Engine Control Unit (ECU), which adjusts the fuel injection timing and rate based on engine load, speed, and injection duration. We constructed comprehensive injection rate maps for both pre- and main injection pulses, focusing on critical variables such as injection timing, duration, fuel flow rate, and common rail pressure. The model was validated against available literature data, showing strong agreement with the numerical results. Our findings indicate a significant increase in engine efficiency and a reduction in emissions compared to traditional injection systems. We have thoroughly discussed and analyzed these results.