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Understanding Direct Injection Engines and How They Work

The technology behind direct injection engines isn’t new. It was first used in 1925 by Swedish engineer Jonas Hesselman but gained popularity only around 20 years ago. Today, you’ll find direct injection under the hoods of about half of the cars on the road in the United States. Direct injection engines are typically more complex and expensive for auto manufacturers to produce than traditional engines. However, the payoffs make the complexity and cost worth it, especially as the technology can help make vehicles more fuel efficient.

Discover how direct fuel injection engines operate and how NYADI The College of Transportation Technology in Jamaica, NY, can train you to work on them.

Understanding the Difference Between a Standard and Direct Injection Engine

At their most basic level, engines require fuel, oxygen, and fire to work. The explosive mixture causes the pistons inside the motor to move back and forth rapidly, which drives the crankshaft and powers the wheels.

The most significant difference between a traditional engine and a direct injection engine is how the engine introduces fuel to the explosive mixture. In a conventional engine, fuel mixes with air in the intake manifold before it’s pushed through to the cylinders. The spark plugs ignite the mixture of gas and oxygen within the cylinder and create the chemical energy that powers the vehicle.

In a direct injection engine, the gasoline isn’t premixed with the air. Instead, a fuel pump directly injects fuel into the cylinder, where it then mixes with oxygen before being sparked by the spark plug. To make this work, the cylinders on a direct injection engine have an extra access point for the fuel injectors to spray the gasoline directly into the chamber. Direct injection engines also have high-pressure fuel rails and high-pressure fuel pumps to draw the fuel out of storage and up to the engine at a higher PSI. This system creates more efficient fuel combustion, creating more power using less fuel than a standard engine.

Why Is Direct Injection the Preferred Option for Auto Manufacturers?

While these might seem like small changes compared to a standard engine, these small changes significantly affect how the engine utilizes fuel. Manufacturers (and many consumers) prefer a direct injection engine thanks to its benefits. One of the most significant benefits is increased fuel efficiency. Because of the way a direct injection engine works, the fuel is precisely measured before being sprayed into the cylinder. That means there is less fuel waste. The fuel is also injected at exactly the right time to complete the combustion reaction, which allows for more of the fuel to burn, which in turn produces more energy. More efficient fuel consumption creates more power for the engine using less fuel, making the system much more efficient in terms of power production and operating costs. Burning the fuel more efficiently also means less waste, which means less pollution created in the form of CO2.

Are There Drawbacks to a Direct Injection Engine?

Some of the potential downsides to direct injection include:

  • Needing more costly repairs. Consumer Reports writes that direct injection engines can lose power over time thanks to buildup in the intake valves. While cleaning the intake valves can fix this, the repair can cost drivers a few hundred dollars.
  • Requiring special fuels or fuel-system cleaners. Some car manufacturers are recommending drivers use gasoline without ethanol in their tanks and periodically add a fuel-system cleaner to prevent build-up. That’s an additional expense for a system that already costs more to purchase.
  • Being more expensive to make. Direct injection engines are more costly for manufacturers to produce because of the complexity of the parts involved. Consumers then must pay a premium for a vehicle with a direct injection engine.

Learn How to Repair and Maintain Direct Injection Engines at NYADI

Understanding how these powerful engines operate is the first step to being able to diagnose, repair, and maintain them. With a growing reliance on direct injection systems, having this skill set can put you on an excellent career path. NAYDI The College of Transportation Technology in Jamaica, NY, allows you to earn your associate’s degree in just 15 months so you can help fill the demand for skilled technicians in the transportation industry. Financial aid is available. Request more information or contact an NYADI admissions representative to learn more about how you can get started in automotive and diesel technology today.