Fuel Injection - What, How, and When

September 29, 2023

Fuel Injection Service | LightHouse Automotive

As you slide into the driver's seat, turn the key, and feel your car's engine roar to life, have you ever wondered about what actually happens behind the scenes? At the core of this automotive "ballet" lies a critical component: fuel injection, or, to be exact, the fuel injection system. Its importance is often overlooked, so let's take you on a spin through the fueling system and get you up to speed on the topic!

The Essence of Fuel Injection

Fuel injection, in its essence, is the lifeblood of your car's engine. It's the method by which a precise amount of fuel is delivered directly into the engine cylinders. Unlike older carbureted systems that relied on a mixing chamber, fuel injection systems have revolutionized how engines operate.

How Fuel Injection Works

So, how does this ingenious system work its magic? Let's break it down into simple steps:

  1. Air Intake: Your engine pulls in air through the intake manifold.
  2. Sensors at Play: A network of sensors continuously monitors crucial parameters like air temperature, pressure, engine speed, and throttle position.
  3. F uel Delivery: Based on the data from these sensors, the engine control unit (ECU) calculates the optimal amount of fuel required for combustion.
  4. Precise Injection: The ECU then commands the fuel injectors to spray the exact amount of fuel directly into each cylinder's intake port.
  5. Mixing and Combustion: The fuel mixes with the incoming air, creating a highly combustible air-fuel mixture. When ignited by the spark plugs, this mixture powers your engine.

Types of Fuel Injection

Now that we've covered the basics let's dive into the fascinating world of fuel injection types. There are several variations, each with its own unique characteristics:

Port Fuel Injection (PFI)

In this common type, fuel is injected into the intake port, just before it enters the cylinder. PFI offers good fuel atomization and precise control.

Direct Fuel Injection (DI)

DI takes precision to the next level by injecting fuel directly into the combustion chamber. This results in improved fuel efficiency and power. It can be seen in vehicles, more specifically after the model, as "TDI",  or TDi" - the most popular being models by VW. 

Sequential Fuel Injection
Here, the injectors fire in a precise sequence, timed to each cylinder's intake stroke. This enhances combustion efficiency and reduces emissions.

Throttle Body Injection (TBI)
TBI systems are simpler, injecting fuel at the throttle body. While less precise than other types, they are cost-effective and reliable.

Single-Point Fuel Injection (SPI)
SPI systems use a single injector to supply fuel to all cylinders simultaneously. They are less common in modern vehicles but offer simplicity.


LightHouse Automotive is here for all of your fuel injection system maintenance or repairs. Just schedule an appointment, and the team will gladly take it from there.

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