What is the difference between direct injection and multi-point injection?
2 Answers
Engine direct injection and multi-point injection differ in the following aspects: Different installation positions of fuel injectors: Multi-point injection fuel injectors are installed at the end of the intake manifold, with fuel spray directed into the intake ports of each cylinder; the air-fuel mixture is formed outside the cylinder. Direct injection fuel injectors are installed on the cylinder head, with fuel directly sprayed into the cylinder; the air-fuel mixture is formed inside the cylinder. Different fuel injection pressures: Multi-point injection operates at a fuel injection pressure of 2.5bar to 4bar; direct injection operates at a fuel injection pressure of 40bar to 400bar, with a trend towards even higher pressures.
As an auto mechanic, I often see the difference between direct injection and multi-point fuel injection in the workshop. Direct injection sprays gasoline directly into the engine cylinder for combustion, offering higher combustion efficiency, more aggressive power output, especially strong acceleration at low RPMs, and some fuel savings. However, it tends to accumulate carbon deposits and requires regular cleaning of the throttle body or fuel injectors; otherwise, performance may decline. Multi-point fuel injection, on the other hand, sprays fuel into the intake manifold for each cylinder, ensuring a more uniform mixture of air and fuel. This results in smoother and more stable driving, fewer issues, and simpler maintenance. Generally, direct injection suits high-performance new cars, such as sports cars or some high-efficiency models, while MPI is more common in regular family cars due to its reliability. However, budget considerations are important when choosing, as direct injection maintenance tends to be more expensive.
