Electronic injection system: operation and parts

The electronic injection system is the one that supplies the fuel to the engine, allowing much more precise control of how much goes into the combustion chamber.

Thanks to that, fuel consumption is lower than in the old carbureted engines. In addition to many other advantages such as: greater adaptability to different working conditions, a smaller intake duct wet area and savings in mechanical elements such as the reprise pump or the idle jet, which are not necessary in injection.

Parts of the electronic injection system

This saving of mechanical elements has as its counterpart a large number of electronic elements such as sensors and actuators. These are the ones that really allow for that adaptability of the engine and a much more stable operation.

We will list and describe each of the electronic injection system parts, because it is not limited to injectors and fuel lines.

• Electric fuel pump and level sensor: responsible for measuring the amount of fuel and pumping it out of the tank.
• Fuel filter: traps possible impurities in the fuel so that they do not reach the electronic injection system or the engine.
• Injection rail or Common Rail: it allows to store the amount of fuel necessary for the engine, regardless of the phase of use, in addition to damping the pulsations in the fluid of the injectors opening and closing.
• fuel pressure regulator: maintains the fuel pressure at a constant level to prevent damage to the injectors or lines of the electronic injection system. When the pressure is very high, it opens a valve that returns the excess to the tank.
• piezo injectors: they are the ones that supply the fuel in the combustion chamber (direct injection) or in the intake (indirect injection), where it mixes with the air.
• ignition coils: responsible for achieving the proper voltage so that the spark plugs can ignite the fuel-air mixture
• Throttle body with its position sensor: It is a butterfly type valve that controls the amount of air that goes to the engine.

• Plugs: produces the spark necessary for the fuel to ignite in the combustion chamber
• Air flow sensor: also called MAF (Mass Air Flow) sensor, it is the one that measures the amount of air that the engine sucks in at each moment
• Intake air temperature sensor: measures the air temperature to optimize ignition and to be able to correct the proportion of the air/fuel mixture
• Camshaft revolution sensor: allows to know the speed at which the camshaft rotates.
• Knock or detonation sensor: if it detects vibrations caused by knocking, it sends an order to the electronic engine management system to vary the ignition advance and fuel injection
• crankshaft revolution sensor: Detects the speed at which the crankshaft rotates by measuring at the ring gear of the flywheel. Thus, the control unit knows the position of the pistons, can calculate the injection times and control the engine drive.
• coolant temperature sensor: measures the temperature of the engine coolant, to activate the electric fans if necessary.
• EVAP canister gas evaporation control valve: redirects the fuel vapors stored in the activated carbon deposit of the canister, so that they go to the intake manifold and are burned.
• Lambda probe for exhaust case control: Measures the amount of oxygen in the exhaust gas to adjust the air/fuel ratio. There is one before catalyst for that function and another after. The second serves to check the correct operation of the catalytic converter.
• Accelerator pedal position sensor: tells the car's control unit how much the driver presses the pedal, to know the power demand.
• ECU (ECU): it is the Electronic Control Unit in charge of collecting all the data sent by the different sensors mentioned up to here and controlling the motor in the most appropriate way. Hence, it is often compared to the brain of the car.

Operation of the electronic injection system

Now that you have an idea of ​​everything that goes into the fuel injection system, it's easy to understand how it works. The fuel pump extracts the fuel from the tank and makes it travel through the feeding system piping. There is the fuel filter that eliminates the possible impurities that end up appearing in the deposit over time.

The fuel travels to the injection ramp, where it accumulates at the right pressure thanks to the pressure regulator. An element that returns excess fuel to the tank. The switchboard makes them injectors supply the correct amount of fuel and that the precise amount of air enters through the throttle body. All of it thanks to the sensors aforementioned. The reels ignition provide the proper voltage so that the plugs ignite the mixture (gasoline engines). In diesel engines, ignition is produced by the pressure exerted on the mixture of air and diesel.

To this we must add that there are many types injection, so there are more elements depending on the system. For example, direct injection engines have high pressure pump, so that the electronic injection system has the correct pressure (approximately between 50 and 100 bar). Otherwise the injectors would not atomize the fuel enough to make a good mixture in the combustion chambers.

Definitely…

Regarding the mechanical injection systems, the injection system electronics takes much advantage of them, since in addition to greater control over the mix, allows higher injection pressures.

The basic operation is as follows: control unit receives information from different sensors distributed by the engine, such as the cost of air in the intake, the temperature of the engine, or the revolutions at which it turns.

With these data, the control unit consults its distribution map and decides how long the injectors have to be open., that's when it sends a signal electronics to the injector so that the shut-off needle is removed and allows fuel to be injected.

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Depending on how many injectors there are, the injection can be single point, if there is an injector for all cylinders (it would be something similar to the carburettor), or multipoint, if there is one injector (or more) per cylinder.

It can also be direct injection, if produced in the same combustion chamber, or indirectIf it occurs in a separate chamber, this is useful because more turbulence is generated, but today with the widespread use of turbocharging, this is no longer necessary.