Fuel injectors are complex systems of valves, pumps and fuel injectors that deliver a mixture of fuel and air into the engine. It is essential that the right amount is released so that the engine is able to perform combustion and the right rate. If not, enough fuel is injected then the engine will not be able to generate enough power to reach the desired speed. If too much fuel is injected, then the engine will flood and cease to work. For this reason, the efficiency of fuel injectors hugely effects lifespan of the engine as well as the amount of harmful carbon emissions that end up in the atmosphere.
Carburetors were the traditional tools used to create the right mixture of air and fuel. However, they are infamously unreliable because they cannot guarantee that each valve will inject the same amount of fuel to the engine. This is because the carburetor will be closer to some fuel injection valves than others. One solution was to use twin-carburetors, however their reliability wanes quickly because it’s almost impossible to tune and synchronize them as they age.
Most modern cars are now installed with fuel-injected engines which are more powerful, use less fuel and reduce harmful emissions.
How is fuel injected?
Usually, fuel is fired into an inlet port by an injector so that it can mix with right amount of air before being fed into the engine. Fuel injectors pressurize the fuel so that that it sprays out in a fine mist and mixes with air from the inlet manifold or port. Once mixed with air, the fuel enters the combustion chamber of the engine where it is turned into the energy needed to make the car move.
The most accurate type of fuel injectors are multi-point injectors. These are able to deliver precisely the same amount of fuel and air to the engine through each cylinder. However, these are very expensive and difficult to replace when they malfunction.
It is more common for cars to be fitted with single injectors. They are not as efficient in their delivery of equal fuel from each cylinder, but they are much cheaper and easy to replace.
What is an injector?
Injectors have nozzles that are screwed into inlet manifolds or cylinder heads. They are angled precisely so that the fuel is sprayed directly at the inlet valve.
Injectors can be one of two types: continuous injectors or pulse injectors.
When the engine is running, continuous injectors squirt fuel into the inlet port at all times. In this type of system, the injector does not control the amount of fuel sprayed itself. In this way it is much like a tap that is turned tighter and looser by the command of a mechanical or electrical system.
Pulse injection does not operate continuously. Fuel is sprayed into the engine with a burst motion. This is synchronized with the induction stroke of the cylinder to ensure that a precise mixture of fuel and air reaches the engine effectively. Again, the fuel bursts can be injected using mechanical or electrical command units.
Older cars would usually have mechanical command systems, but they are very complex and unreliable. Furthermore, they are not particularly responsive to the operator easing off the throttle. This wastes fuel and drives up the running cost of a car.
Since electronic systems are becoming cheaper and cheaper to produce almost all modern cars will be installed with electronic fuel injectors (EFi).
Advancements in Engine Management
Technology like the Bosch Motronic incorporates the function of fuel injectors into a more efficient and holistic system. The level of oxygen in exhaust gases can be monitored in order to gauge the exact amount of fuel needed for desired combustion levels. This makes fuel consumption much more economical and reduces running costs of a vehicle. Furthermore, engine management systems are able to notice when there is an imbalance in ignition timing and fuel delivery. In turn, the engine can automatically tune itself back to normal. As a result, dangerous emissions and fuel consumption is reduced while performance is increased.
The car industry has come a very long way in the last 60 years. Engines of a similar power can now be run with as little as 30 times less fuel. This helps to reduce air pollution and makes the running costs of cars more affordable for the average consumer.