Fuel injectors generally spray more fuel as RPM increases, but it’s not just RPM that determines the amount of fuel injected. The engine’s ECU (Electronic Control Unit) calculates fuel delivery based on multiple factors, including:
- Throttle position (how much air is entering)
- Mass airflow sensor (MAF) or manifold absolute pressure (MAP) readings
- Engine load
- Oxygen sensor feedback (to maintain the proper air-fuel ratio)
At higher RPMs, the injectors fire more frequently and may open longer (higher duty cycle) to deliver the necessary fuel. However, if the engine is running at high RPM but under low load (like cruising on the highway), the ECU may reduce fuel delivery to maintain efficiency.