Electronic Fuel Injection System Explained | Merits and Demerits

Electronic Fuel Injection (EFI) System

Electronic fuel injection (EFI) system is used both in gasoline and diesel engines.

There are many problems with the carburetors used for preparing charge in the gasoline engines.

Some of them are

1. Non-uniform distribution of fuel in a multi-cylinder engine.
2. Poor breathing capacity (volumetric efficiency) of the engine.
3. Problem of detonation.
4. Fuel loss due to scavenging in two stroke engines.

To eliminate these problems modern day gasoline engines use Electronic fuel injection.

Electronic fuel injection (EFI) system use engine sensors, a computer and solenoid operated fuel injector to meter and inject right amount of fuel into the cylinders.

An electronic control unit receives information in the form of electric signals from the sensors.

These sensors are mounted at different parts of the engine.

On the basis of requirements of the engine, electronic fuel injection system injects right amount of fuel into the engine.

It results into the less un-burnt fuel in the emission.

Typical sensors used in the electronic fuel injection (EFI) system

1. Exhaust gas or oxygen sensor
2. Engine temperature sensor.
3. Air flow sensor
4. Air inlet temperature sensor
5. Throttle position sensor
6. Manifold pressure sensor
7. Camshaft position sensor
8. Knock sensor

Merits of electronic fuel injection (EFI) system

1. Improvement of volumetric efficiency of the engine
2. Manifold wetting is eliminated due to direct fuel injection into the cylinder
3. Atomization of fuel is independent of cranking speed, hence good atomization even at low speed.
4. Better atomization and vaporization results in less knocking.
5. Formation of ice at throttle plate is eliminated.
6. Distribution of fuel is independent of vaporization hence low volatile fuels can also be used.
7. Variation of air fuel ratio is almost negligible, which results in good engine performance.
8. Position of injection unit is not so critical, hereby height of engine can be less.

Demerits of electronic fuel injection (EFI) system

1. High maintenance cost.
2. Difficulty in servicing.
3. Possibility of malfunction of some sensors.

Image (also featured) attributions: By Vegavairbob at English Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12013462