How Does Your Car’s Fuel Injection Work?
If compared side by side, today’s vehicles would look a world apart from their predecessors from a generation ago. The differences don’t stop at the exterior; they can be found deep under the surface (or, under the hood). The parts that were found in yesterday’s automobiles have been replaced by components which are more efficient, sophisticated, and durable.
While many older performance vehicles still use carburetors, newer models have largely moved to electronic fuel injection (EFI). Through a carefully-designed procedure of multiple parts working in seamless unison, your car’s EFI can deliver more power in a variety of driving circumstances.
In this article, I’ll describe the components which make up your electronic fuel injection assembly. I’ll also explain their respective functions as well as how they work together.
The Engine Controller
Often called the brain of your vehicle, the engine controller is a computer which keeps track of a variety of things while you’re driving. For example, it will monitor the position of your throttle, the oxygen sensor, and engine emissions. It also takes note of your current driving conditions. Whether you’re moving up a steep hill or coasting easily along the highway, the computer will identify the amount of gas required to deliver the performance you need.
Input Sensors
Computer programmers are familiar with the phrase “garbage in, garbage out.” The engine controller works on the same principle. In order to identify the amount of fuel required, it needs data. It receives that data from a number of input sensors. For example, it will watch a coolant temperature sensor to determine your engine’s operating temperature. It will monitor an oxygen sensor to identify the proper air and fuel mixture needed to maximize performance. There are also manifold absolute-pressure inputs and engine speed sensors that must be monitored.
As long as these sensors function properly, the computer can make accurate assessments. If one (or more) fails, the bad input data can cause a loss in performance.
The Injector
The injector is the order taker of your vehicle’s EFI system. As the inputs are delivered to the computer, the computer calculates how much fuel is optimal given your driving circumstances. The “order” is sent to the injector which fires the calculated amount into the combustion chamber. The firing is done as the injector’s nozzle opens and closes; the amount of time the nozzle is open is called its pulse width.
Your vehicle’s EFI system is able to deliver more efficient performance than a carburetor. Because a carburetor operates mechanically, it cannot effectively monitor all of the variables which change while you’re driving. By contrast, EFI leverages your vehicle’s computer to inject precise amounts of fuel based on airflow, engine temperature, voltage, rpms, and other criteria.
While the system is not as simple to fix if problems develop, EFI represented an important evolution in automotive technology.