Multi Port Fuel Injection (MPFI) is a fuel delivery system characterized by the use of one dedicated fuel injector per intake runner, with one intake runner per cylinder.

In a standard four-cylinder Honda engine configuration, this system utilizes four individual injectors to deliver fuel directly into the intake port of each cylinder.

System Characteristics#

• Individual Delivery: Each cylinder receives fuel from its own dedicated injector, allowing for precise control over the air-fuel mixture for every combustion event.
• Intake Configuration: The system requires an intake manifold design where each cylinder has a distinct runner, ensuring that the fuel spray is directed toward the intake valve.
• Engine Management: MPFI systems are controlled by the Engine Control Unit (ECU), which manages injector pulse width and timing based on data from various engine sensors.

Note

MPFI is distinct from Throttle Body Injection (TBI), which typically uses one or two injectors located in a central throttle body to supply fuel to all cylinders simultaneously.

Benefits of MPFI#

• Improved Fuel Atomization: By placing the injector closer to the intake valve, the fuel is better atomized before entering the combustion chamber.
• Increased Efficiency: Individual cylinder fueling allows the ECU to compensate for minor variations in airflow between cylinders, leading to smoother idle and improved throttle response.
• Emissions Control: Precise fuel delivery enables more effective operation of the catalytic converter and oxygen sensor feedback loops.