The function of the MPFI system :
The main function of this system is to supply a proper ratio of gasoline and air to the cylinders.
These systems function under two basic arrangements.
In this arrangement, the injector is placed on the side of the intake manifold near the intake port. The injector sprays gasoline into the air, inside the intake manifold and mixes with the air in a uniform manner. This mixture of gasoline and air then passes through the intake valve and enters into the cylinder.
Each cylinder is provided with an injector in its intake manifold. For every cylinder, there is one injector. If there are 5 cylinders then there will be 5 injectors.
Throttle body injection system :
With the use of a throttle valve controlling the amount of air entering the intake manifold similar to the carburettor throttle system.
The injector is placed slightly above the throttle body. The injector sprays gasoline into the air in the intake manifold where the gasoline mixes with the air. This mixture then passes through the valve and enters into the intake manifold.
Multi-point fuel injection systems are classified into two types :
The main function of this system is to supply a proper ratio of gasoline and air to the cylinders.
These systems function under two basic arrangements.
- Port injection
- Throttle body injection
In this arrangement, the injector is placed on the side of the intake manifold near the intake port. The injector sprays gasoline into the air, inside the intake manifold and mixes with the air in a uniform manner. This mixture of gasoline and air then passes through the intake valve and enters into the cylinder.
Throttle body injection system :
With the use of a throttle valve controlling the amount of air entering the intake manifold similar to the carburettor throttle system.
The injector is placed slightly above the throttle body. The injector sprays gasoline into the air in the intake manifold where the gasoline mixes with the air. This mixture then passes through the valve and enters into the intake manifold.
Multi-point fuel injection systems are classified into two types :
- D-MPFI
- L-MPFI
D-MPFI system :
It is the manifold fuel injection system, the vacuum in the intake manifold is first senses the volume of air by its density.
The functioning of D-MPFI system :
As shown in the figure above as air enters into the intake manifold, the manifold pressure sensor detects the intake manifold vacuum and sends the information to the ECU. The speed sensor also sends the information about the RPM of the engine to the ECU. ECU sends commands to the injector to regulate the amount of gasoline supply for injection. When the injector sprays fuel in the intake manifold the gasoline mixes with the air and the air-fuel mixture enters the cylinder.
L-MPFI system :
The L-MPFI system is a port fuel-injection system. In this type, the fuel metering is regulated by the engine speed and the amount of air that actually enters the engine. This is called air-mass metering or air-flow metering.
The function of L-MPFI system :
As shown in the figure above the air enters into the intake manifold, the airflow sensor measures the amount of air and sends information to the ECU. Likewise, the speed sensor sends information about the speed of the engine to the ECU. ECU received the information and sends appropriate commands to the injector, in order to regulate the amount of gasoline supply for injection. When the injection takes place, the gasoline mixes with the air and the air-fuel mixture enters the cylinder.
The functioning of D-MPFI system :
As shown in the figure above as air enters into the intake manifold, the manifold pressure sensor detects the intake manifold vacuum and sends the information to the ECU. The speed sensor also sends the information about the RPM of the engine to the ECU. ECU sends commands to the injector to regulate the amount of gasoline supply for injection. When the injector sprays fuel in the intake manifold the gasoline mixes with the air and the air-fuel mixture enters the cylinder.
L-MPFI system :
The L-MPFI system is a port fuel-injection system. In this type, the fuel metering is regulated by the engine speed and the amount of air that actually enters the engine. This is called air-mass metering or air-flow metering.
The function of L-MPFI system :
As shown in the figure above the air enters into the intake manifold, the airflow sensor measures the amount of air and sends information to the ECU. Likewise, the speed sensor sends information about the speed of the engine to the ECU. ECU received the information and sends appropriate commands to the injector, in order to regulate the amount of gasoline supply for injection. When the injection takes place, the gasoline mixes with the air and the air-fuel mixture enters the cylinder.