Simply put, electronic fuel injection (EFI) is a system that delivers or injects fuel into an engine’s induction system or directly to the engine combustion chambers.
An improvement over a carburetor or early mechanical fuel injection, EFI employs electronically controlled injectors to spray a precise amount of fuel directly into the intake manifold or combustion chamber, ensuring the engine receives the optimal air-fuel mixture for efficient combustion. This process is controlled by the vehicle’s Engine Control Unit (ECU), which adjusts the fuel delivery based on various factors like engine speed, temperature, and load.
Fuel injection also offers several advantages over carburetors, including better fuel efficiency, improved engine performance, and lower emissions. By delivering fuel more accurately, the system ensures that the engine operates smoothly and uses less fuel, which means better fuel efficiency. Additionally, fuel injection systems help reduce harmful exhaust emissions, by precisely controlling fuel flow for more complete combustion.
There are three main types of fuel injection systems: port fuel injection (PFI); gasoline direct injection (GDI); and throttle body injection (TBI).
PFI delivers fuel to the intake manifold just before the intake valve, while GDI injects fuel directly into the combustion chamber. TBI, an older form of fuel injection, uses one or two injectors mounted in a throttle body to deliver fuel into the intake manifold, functioning similarly to a carburetor but with better fuel atomization and electronic control. Both PFI and GDI are designed to optimize the fuel-air mixture and improve engine efficiency, but GDI tends to offer even better performance and fuel economy.
You can learn more about it in this standalone article: What Are the Different Types of Fuel Injection Systems?
Fuel injection has become the standard in modern vehicles due to its effectiveness and environmental benefits.
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Fuel injection is a complex and nuanced topic, so we have plenty of more resources to help you better understand how to service and upgrade your EFI system. Check out the links below to get started.
- 5 Things to Consider When Converting to Electronic Fuel Injection
- EFI 101: Mass Air vs. Speed Density
- How a Direct Injection Engine Affects Your Oil
- Will My New EFI System Work With My Setup?
- How Electronic Fuel Injection (EFI) Affects Cam Idle
- 3 Reasons to Consider a Self-Learning Fuel Injection System
- Fuel Pressure Ratings & How They Affect Your Engine
We also spoke with the fuel injection experts at Holley all about EFI conversions, troubleshooting, and general fuel system tech. Check out the whole interview in this episode of The OnAllCylinders Podcast:
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