By the mid-1980s, the long reign of the carburetor was beginning to wane with the emergence of a new method of fueling. The Electronic Fuel Injection (EFI) system, much more efficient and economical than its predecessor, began to be widely used in vehicle manufacturing and prevails to this day.

It was an integrated electronic system that measured, adapted and precisely controlled all stages of fuel injection into the engine. The entire process was optimized through an electronic control unit (ECU) that received data from several sensors and performed complex mathematical calculations to, among other things, maintain the best possible air/fuel mixture, regardless of external factors.

The reason for the rapid popularization of electronic injection was due to several reasons:

In addition, the main competitor of the electronic system was the old carburetor, which greatly facilitated the large-scale adoption of electronic injection.

Before delving into the complex and fascinating electronic injection system, we need to understand how the carbureted system and the electronic injection work, as well as their main differences.

Carburetors provide fuel control by dynamic means, where a pressure difference controls fuel flow along with turning of airflow control valves. The relationship between air flow and fuel flow is essentially mechanically adjusted.

Various methods have been used over the years in an attempt to provide a way to compensate for different operating conditions in carbureted systems. None of these ways was as efficient as electronic injection.

In the electronic injection system the carburetor is eliminated. Air flow regulation continues to be performed using a butterfly or valve, however the amount of fuel used is electronically controlled by the system. The proportion of fuel and air supplied to the engine can be regulated independently.

The EFI provides delivery of the required fuel/air mixture based on information provided by various sensors, including the air temperature sensor, engine temperature sensor, manifold pressure sensor, oxygen sensor, RPM sensor, and the sensor. throttle position.

An electronic control unit (ECU) performs the calculations that are necessary to optimize both the fuel supply and the ignition system. EFI allows the air/fuel ratio to be continuously adjusted according to operating conditions (altitude and temperature) and engine requirements (throttle opening, cold start, hot start, etc.).

Engines equipped with electronic injection generally offer greater power and torque than a carbureted version of the same. In carburettors it is difficult to optimize power/torque across the various ranges of rotational speeds, whereas EFI systems are able to adapt throughout all operating cycles.

In addition, electronic injection can at the same time compensate for other factors in order to maintain optimal performance. Normally injection engines produce about 5% to 10% more energy than their carbureted version.

If the heart of a car is its engine, we can say that its brain is the Engine Control Unit (ECU). The ECU optimizes the engine's performance by making decisions based on data collected through the sensors that make up the electronic injection system. This central unit is responsible for carrying out four fundamental functions for the operation of the vehicle:

Before going into detail on how the ECU accomplishes its tasks, let's walk through the path taken by a drop of gasoline that is put into your car. In the tank, fuel is sucked in by an electric pump. This device sends gasoline through rigid fuel lines to the distributor tube.

A vacuum pressure regulator at the end of the distributor tube ensures that the fuel pressure in the tube remains constant in relation to the inlet pressure and sends the surplus back to the tank. Immediately connected to all distributors are the injection valves, which remain closed until the ECU decides to send fuel to the cylinders.

Typically, injection valves have two connections. One is connected to the battery via an activation relay and the other is connected to the control unit. When the ECU decides to send fuel to the combustion chamber, it sends an electric pulse to the injector, which closes the circuit and provides the passage of electric current to the solenoid.

The magnet at the top of the plunger is attracted by the magnetic field generated by the current in the solenoid, causing the valve to open. Once at high pressure in the manifold, opening the valve sends fuel at a high velocity through the injector's spray tip. The time during which the valve will be open and, consequently, the amount of fuel sent to the cylinder, depends on the width of the pulse sent by the ECU.

When you press the accelerator pedal, the throttle position sensor sends a signal to the ECU. The manifold pressure sensor determines how much air is entering the intake manifold and also forwards this information to the control unit. The ECU uses this information to decide how much fuel should be injected into the cylinders to maintain the stoichiometric mixture.

The computer continuously uses throttle position verification to measure the amount of air admitted into the system in order to adjust the electrical pulse sent to the injection valves, ensuring that the proper amount of fuel is introduced.

In addition, the ECU uses the oxygen sensor to find out how much oxygen is present in the exhaust. The oxygen content in the exhaust gases provides an indication of how well the mixture is burning. Between the throttle position, manifold pressure and oxygen meter sensors, the computer fine-tunes the pulse it transmits to the injection valves.

To function perfectly, the electrical current destined for the spark plugs must be supplied at very precise points within the engine's operating cycle. The spark, produced through the spark plug, is optimized in relation to the position of the piston. This allows the engine to take a maximum amount of work from the expanding gases resulting from combustion.

Based on data from the cylinder position sensor, also known as the rotation sensor and the other sensors mentioned above, the ECU determines when to trigger the coil and, consequently, the spark plugs. The ECU continuously receives information from the RPM sensor and uses it to optimize the ignition.

It is a very complex system, with many components working together. That's why we brought a small simplified diagram with all the system's members and their respective positions in the operations cycle.

For all their complexity and genius, electronic fuel injection systems are inherently more reliable than carbureted ones. This stems from its ability to maintain optimal air/fuel ratios throughout the entire operating cycle. Unexpected engine stalls, excessively worn spark plugs and other problems associated with disproportionate mixtures are eliminated.

Carburetors tend to be more maintenance-intensive and require constant adjustments. Engines equipped with an electronic fuel injection system remain constantly in perfect tune. This not only improves reliability, but also reduces the amount of routine maintenance required for satisfactory performance.