Difference Between Direct Injection and Electronic Fuel Injection in Engines?
2 Answers
The biggest difference between a direct injection engine and a multi-point electronic fuel injection engine lies in the fuel injection method. The evolution of automotive engine fuel injection systems, from the earliest carburetors to multi-point electronic fuel injection, has always aimed at improving combustion efficiency by enhancing fuel injection efficiency. The advent of direct injection technology has significantly increased the mixing efficiency of gasoline and air within the cylinder, leading to more complete combustion. Below is a detailed introduction to these two engine technologies: 1. Direct Injection Technology: This is a new and relatively advanced fuel injection technology that uses high pressure to directly inject fuel into the combustion chamber of the cylinder. Unlike the traditional method where the fuel injector is placed in front of the intake valve, what reaches the intake valve is pure air instead of an air-fuel mixture. This allows the direct injection engine to determine the amount of air entering the cylinder for combustion based on the intake valve opening time and then inject the corresponding amount of fuel according to the vehicle's operational needs. 2. Multi-point Electronic Fuel Injection Technology: In gasoline engines, the fuel injection process occurs in the intake manifold, where the control program issues specific timing commands to the electronic fuel injectors. Multi-point injection is relative to single-point injection. Traditional gasoline engines use a carburetor in the intake manifold to mix gasoline with air, forming a combustible mixture that enters the cylinder and is ignited by the spark plug during the compression stroke. Due to variations in the length and position of the intake manifolds, the amount and timing of the air-fuel mixture injected into each cylinder are inconsistent, leading to differences in the working conditions of each cylinder.
The core difference between direct injection and port injection engines lies in the fuel injection location. Port injection typically sprays fuel into the intake manifold, allowing air and fuel to mix before entering the cylinder. Direct injection differs by injecting fuel directly into the cylinder for combustion, resulting in more precise burning. This enables higher engine efficiency and stronger power output, making direct injection vehicles accelerate faster, though the system is more complex and may require additional maintenance attention. Port injection engines are relatively simpler, lower in cost, and have fewer carbon deposit issues, making them suitable for daily driving, but their fuel economy is not as good as direct injection.
