The pressure of the Fuel Pump directly affects the atomization characteristics of the injector. When the pressure fluctuation exceeds ±15kPa, the deviation of the spray cone Angle can reach 25%. In the direct injection system in the cylinder, the standard pressure needs to be stabilized at 350kPa (such as the Bosch HDEV5 injector specification). If the output of the Fuel Pump drops to 280kPa, the average diameter of the droplet Sote increases by 30μm, resulting in an 18% decrease in evaporation efficiency. The SAE study in 2023 shows that a 10% pressure deviation causes the air-fuel ratio to deviate from the theoretical value by ±0.8, increases hydrocarbon emissions by 50%, and as a result, the fuel consumption of engines meeting the EPA Tier 3 standard rises by 5.2%.
Low-pressure conditions cause the collapse of spray morphology. Experimental data show that when the pressure is lower than 200kPa, the spray penetration distance shortens by 40%, and the droplet concentration at the edge exceeds 150g/m³. In the 2022 WRC Sweden Grand Prix, a certain team suffered from a clogged fuel pump filter (with a pressure drop of 50kPa), causing the spray cone Angle to sharply decrease from 70° to 45°. The cylinder misfire rate soared to 30%, resulting in a peak power loss of 27kW. At this point, the ECU is required to forcibly compensate the fuel injection pulse width to 5ms (the normal value is 3.2ms), but the probability of fuel wetting the wall still increases by three times.
The high-pressure environment intensifies the system load. When the pressure exceeds 450kPa and the nozzle flow rate exceeds 25m/s, although the diameter of the atomized particles decreases to 15μm (increasing the combustion efficiency by 12%), the nozzle wear rate increases by 300%. The technical announcement of the BMW B48 engine states that after an overpressure of 10% persists for 20,000 kilometers, if the fuel injector flow deviation exceeds ±4%, an adaptive learning program needs to be executed 7 times (each time taking 45 minutes). An extreme case was seen at the 24 Hours of Le Mans in 2021. A certain manufacturer adjusted the pressure to 500kPa in pursuit of power, which led to an 80% increase in the failure rate of piezoelectric crystal actuators and a single repair cost of 2,300 euros.
The optimization plan requires precise and coordinated control. A closed-loop fuel system is adopted to keep the pressure fluctuation within ±5kPa (such as a sensor with 0.5% accuracy provided by Continental), and the uniformity of the spray is improved by 90%. The Tesla Model S Plaid maintains the droplet diameter within the range of 20±2μm under all working conditions through a 10Hz dynamic adjustment mechanism, and the soot emission is only 0.02g/km. The industry consensus follows the ISO 27145 standard. It is recommended to detect the attenuation of the pump pressure curve every 30,000 kilometers driven (the normal attenuation rate is <2%/ year), and calibrate the fuel injectors simultaneously. The comprehensive operation and maintenance cost can be reduced by 34%.