Multi point fuel Injection (MPFI)

Sometimes it is very difficult for a carburetor system to supply the proper air fuel ratio at all the load conditions. The purpose of Multi point fuel injection (MPFI) system is to supply proper air fuel ratio to each cylinder of the engine. For this purpose two types of systems are used:
Port Injection system: In this system one injector is placed in each of the intake manifold near the intake valve. If there is six cylinders engine then six injectors are fitted (one for each cylinder). The injector sprays the fuel (petrol or gasoline) into the air. The fuel air mixture then enters into the cylinder.
Throttle injection system (Single point injection): A single injector is used for spraying the fuel. Injector is placed above the throttle of the throttle body. Air entering the intake manifold is controlled by the throttle valve. The injector sprays the fuel (petrol or gasoline) into the air in the intake manifold. The air fuel mixture then enters into each cylinder.