Port fuel injection is a widely used fuel-delivery system in automotive engines. By spraying fuel directly into each intake port, it helps create a more precise air–fuel mixture, supporting efficient combustion, responsive performance, and reduced emissions.
Unlike older carburetor systems, port fuel injection uses electronically controlled injectors that adjust fuel delivery according to engine conditions. Its design offers a practical balance of reliability, efficiency, and serviceability within modern fuel systems.
Port fuel injection is a fuel-delivery system in which each injector sprays gasoline into the intake port near its corresponding intake valve. The fuel mixes with incoming air before entering the combustion chamber, where it is ignited by the spark plug.
The engine control unit determines the required fuel quantity by processing information from sensors, including engine speed, throttle position, intake-air measurement, and coolant temperature. It then adjusts injector opening time to maintain the appropriate air–fuel mixture.
Unlike throttle-body injection, port fuel injection uses separate injectors for individual cylinders, allowing more precise fuel distribution. Fuel vaporization also benefits from the heat around the intake port, supporting consistent combustion and smoother engine operation.
Port fuel injection can improve drivability, emissions control, and fuel economy compared with older carbureted systems. However, it generally cannot provide the same cylinder-pressure injection capability or potential efficiency gains associated with direct fuel injection.