TVS Vehicles | 23 Jan 2025

Multi-Point Fuel Injection: What It Is and How It Works (MPFI)

Multi-point fuel injection system (MPFI) is an air and fuel mixture system that was developed to replace the carburettor in the engines. Since performance engines required accurate throttle response, carburettors couldn’t match the instant surge of air-fuel mixture required as they lacked an electronic control unit, found in modern vehicles these days.

What is MPFI?

The basic mechanism of an MPFI fuel injection system includes an injector at the front of the inlet valve. Also known as port injection, these injectors inject an optimum quantity of fuel into the combustion chamber, resulting in better atomisation. There are a few parts that work in sync for combustion inside the cylinder.

Fuel pumps draw fuel from the fuel tank to the fuel rail while also maintaining the desired fuel pressure. The sensors collect data on engine parameters, such as engine rpm, vehicle speed, gear, throttle response etc. Based on the ECU’s calculation, the fuel injector sprays the precise amount of fuel for combustion.

In an MPFI system, the fuel pressure regulator is connected to the fuel rail by an inlet and an outlet valve. There is a spring control over the outlet valve opening that controls the amount of fuel that can return. The pressure in the intake manifold significantly changes in sync with the engine rpm.

Components of MPFI

• Fuel Injector: Each cylinder has its own dedicated injector; it sprays a mist of air-fuel mixture inside the intake manifold. The fuel injector provides a precise fuel delivery as per the throttle input.
• Pressure regulator: It maintains a constant fuel pressure in the fuel rail ensuring that each injector has an adequate supply of fuel to be sprayed inside the cylinder.
• Fuel Pump: It delivers a constant supply of fuel from the tank to the injectors as per the required pressure for optimum engine performance.
• ECU: Also known as the engine control unit, this is the brain of an MPFI system. It fetches data from multiple sensors and calculates the optimal amount of air-fuel mixture to be injected.
• Sensors: There are multiple sensors that feed real-time data to the ECU, in order to make precise fuel delivery.

Advantages of MPFI

Since its inception, the MPFI (multipoint fuel injection system) has been a game changer in the automotive industry, by improving fuel efficiency, reduced emissions and enhanced performance. Here are some of its advantages in detail:
• Improved performance: Since the engine gets a calculated air-fuel mixture, the power delivery is precise with optimal combustion and greater torque delivery.
• Emission Control: During each cycle the cylinder gets the precisely required air-fuel mixture, which is initially pressurised and then ignited, resulting in complete combustion without any fuel loss, resulting in greater emission control.
• Reliability: It is a sophisticated system, deploying simple yet effective working. Unlike carburettors that have to deal with fuel boiling and vapour locking, causing sudden engine heating. There is nothing as such in the MPFI system to hamper the injection cycle, resulting in a longer working life.
• Ease of Cold Start: When the engine is cold, the air entering the carburettor is also cold, resulting in a lean air-fuel mixture, not ideal for combustion. MPFI engines use a slightly different approach. Just before combustion, the air-fuel mixture is compressed, ensuring a rich enough fuel ideal for ignition. It is also due to the fact that MPFI engines adapt to the temperature changes swiftly.

TVS Motor Company has embraced fuel injection technology (RT-Fi). In 2024, the company introduced a new engine for its flagship lineup in TVS Motosoul 4.0, namely: - TVS RTX-D4, this new 6-speed gearbox is completely developed in-house by TVS Motor.

It gets a forward inclined posture, rather than the traditional reverse inclined, this new layout offers room for a deflector plus duct system for efficient thermal management. The engine also excels in linear torque characteristics for a seamless ride experience.

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