MPFI vs Direct injection – Difference explained with Pdf

The main differentiating point for the MPFI vs Direct injection is that in the MPFI system the fuel is injected into the intake manifold while in direct injection system the fuel is directly injected into the cylinder.

Before discussing the difference between the MPFI and the direct injection system let’s know about each of them in brief.

What is Multi-point fuel injection?

MPFI is the type of fuel injection system used in an IC engine that helps to inject fuel separately to each cylinder by use of individual fuel injector provided above the inlet valve of each cylinder.

The MPFI system helps to inject the proper quantity of fuel into each cylinder on exact time.

In the MPFI system, the operation of fuel injectors is controlled by the engine control unit (ECU). The ECU takes input from various sensors like throttle sensor, crankshaft position sensor, the fuel pressure sensor to control the flow of fuel from the injector.

What is Direct injection system?

It is the type of fuel injection system in which the fuel is directly injected into the combustion chamber. As the fuel is directly injected into the high-pressure combustion chamber therefore this system uses a high-pressure fuel injector pump for its operation.

Previously in direct injection system, the flow of fuel to the engine is controlled by the use of a governor. The basic components of this direct injection system are fuel injector pump, injector, filter, feed pump etc.

MPFI vs Direct injection:

Sr. No.Multi-point fuel injection (MPFI)Direct injection (DI)
1]In the MPFI system, the fuel is injected into the intake manifold, above the intake valve.In a direct injection system, the fuel is injected directly into the combustion chamber.
2]In the MPFI system, the fuel is injected at the time of suction stroke.In direct injection system, the fuel is injected after the compression stroke.
3]It operates at a comparatively lower pressure than DI.It operated at a higher pressure than MPFI.
4]It is less efficient than DI system.It is more efficient than the MPFI system.
5]It requires only a low-pressure pump for its operation.It requires a feed pump and fuel injector pump for its operation.
6]The engine emissions are comparatively higher.It has lower engine emissions.
7]It is less expensive.It is more expensive than MPFI.
8]There are no modifications in the piston for the fuel injection.The piston is modified for efficient working.

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