In the previous articles, we have discussed the functional requirements of the Fuel injection System, and the difference between the Fuel injector and the Carburetor. In this article, we are going to discuss the Electronic Fuel Injection System.
Electronic Fuel Injection System
As we have discussed the Petrol injection system, in the modern engines, In which the fuel injection system uses the sensors, a computer and a solenoid operated fuel injector to meter and inject the right amount of fuel into the engine cylinder called the Electronic Fuel Injection system. (EFI). These systems use the electrical and electronic systems to monitor and control the engine operations.
Usually, in every modern engine, there is this ECU (Electronic control unit). This unit will operate all the devices such as the injectors, ignition system and the other engine related devices. with the help of received electrical signals in the form of a current or voltage from the various sensors.
This results in the better performance of the engine by operating every device at the correct timing and in a perfect sequential manner.
So what kind of sensors need to be involved in the engine? So here we go… the list of sensors that we need in a modern engine to use the Electronic fuel injection system with the ECU.
- Exhaust gas or Oxygen sensor
- Engine Temperature sensor
- Airflow sensor
- Air inlet temperature sensor
- Throttle position sensor
- manifold sensor
- Crankshaft position sensor
- Knock sensor
Operation of an Electronic Fuel Injection System
The fuel injector in the Electronic fuel injection system is nothing but a fuel valve. This valve will be operated with the computerized signal to actuate by means of the magnetic force by an injector armature. By this way, the fuel valve will be open and closes.
The pulse width in the signal will represents the period for the injector to keep open. This period (Pulse width) will be controlled by the computer based on the signals received from the various sensors listed above.
During the full load conditions on the engine, the computer will sense that the wide opening of the throttle, high intake manifold pressure and the high inlet airflow. With this sensing information from the sensor, the ECU will increase the injector opening (Pulse width to enrich the mixture to enable the engine to produce high power.
During Engine Idling or low speed or cruising, the ECU will shorten the pulse to make the mixture leaner to make the engine fuel economy.
When the engine is cold, it’s hard to start the engine. The electronic fuel injection system has a cold start injector too. It is an extra injector that sprays fuel into the centre of the engine intake manifold to start the engine easily. it is the same purpose as the carburettor choke. this helps the engine to start up in very cold weather.
Advantages of Electronic Fuel Injection System
- Improved Volumetric efficiency
- Formation of ice in the throttle plate is eliminated.
- Atomization of the fuel is independent of the cranking speed and therefore starting of the engine is quite easier.
- position of the injection system is not so critical and thereby the height of the engine can less.
- Less volatile fuel can be used.
- The fuel will be injected close or into the cylinder so the wetting of the manifold can be avoided.
Dis-advantages of Electronic Fuel Injection System
- High Maintenance cost
- Possibility of malfunctioning of the sensor
- Servicing complexity
We have discussed how the Electronic fuel injection system can function in different operating speeds, drawbacks and advantages. If you have any further thoughts on this topic, let us know in the comment section below.