How to Distinguish Between Multi-Point Fuel Injection and Direct Injection?
2 Answers
The difference between multi-point fuel injection and direct injection lies in their methods: multi-point fuel injection is accomplished through electronic fuel injectors; direct injection involves directly injecting fuel into the cylinder to mix with the intake air. Direct injection technology is gradually replacing multi-point fuel injection, and direct injection can also be considered another form of electronic fuel injection. In direct injection, the fuel injector is moved from the intake manifold to the inside of the cylinder, so the amount of fuel-air mixture is not affected by the opening and closing of the intake valve but is directly determined by the computer for the timing and quantity of fuel injection. Both multi-point fuel injection and direct injection belong to electronic fuel injection, where fuel is electronically controlled and injected into the intake pipe to mix with air, and then the engine's intake stroke draws the fuel-air mixture into the cylinder.
I've been driving a taxi for fifteen years and have used both types of engines. The simplest way to tell them apart is by listening to the sound—direct injection engines sound like machine guns rattling during cold starts, while multi-point fuel injection is much quieter. When driving normally, cars with direct injection have lightning-fast throttle response; step on it and you'll shoot forward, and at red lights, the fuel consumption gauge can drop below 1.0. But after a hundred thousand kilometers or so, they're prone to triggering the check engine light, requiring frequent carbon cleaning. Multi-point fuel injection may feel a bit sluggish during acceleration, but maintenance is cheaper—a roadside shop can clean the injectors for just two hundred bucks, making it perfect for drivers like us who are on the road all day. Last time, I saw a rookie driver get tricked by the dealership into spending three grand to clean the direct injection system—it really doesn’t need to be that delicate.
