Engines combust a mix of fuel and air inside their chambers in order the move the pistons that create the vehicle’s forward and backward motion. This motion is transferred to the wheels, which makes the car drive. However, how the fuel is delivered to the cylinders depends on the type of fuel injection system present in the vehicle. Different types of injection systems yield very different results.
1. Throttle Body Injection System
The throttle body injection (TBI) system is one of the first types of injection systems ever used by vehicles. TBIs work in a manner very similar to a carburetor. The fuel is still sucked into the cylinders because of the suction created by the engine. However, TBIs are controlled by an electronic computer within the vehicle. The computer provides more accuracy by determining the amount of fuel that should be deposited into the engine. This accuracy ensures less fuel is wasted and allows the vehicle to run more efficiently.
2. Multi-Port Fuel Injection System
Multi-port fuel injection (MPFI) systems operate just how their name implies: with multiple intake ports. They are a step up from throttle body injection systems, which only have a single port. MPFIs are mounted onto each intake port. These intake ports are located just on the outside of the engine’s cylinders. In MPFI, each cylinder receives its own direct spray of fuel. So in a six-cylinder engine, there would be six injection ports. All individual injectors spray at the same time. This can sometimes lead to issues when leftover fuel is left behind while waiting for the next intake period. The fuel may condense into a liquid form and then be rendered unusable by the engine. Although MPFI is more efficient than TBI, sequential fuel injection offers even better fuel efficiency.
3. The Sequential Fuel Injection System
Sequential fuel injection systems are almost exactly the same as MPFI. However, their one critical difference overcomes the main issue with MPFI systems. Sequential, otherwise known as timed injection, triggers each nozzle individually at the optimized time to ensure all the fuel makes it into the intake valve. This process can help reduce fuel waste. In addition, it provides the most optimized ratio of fuel to air in the combustion chambers.
4. The Direct Injection System
Direct injection systems differ from other fuel injection systems because they bypass the intake valves and deposit fuel straight into the cylinder’s combustion chamber.
Direct injection has been used in diesel engines since 1920. However, performance vehicle manufacturers like Audi and BMW are beginning to use the direct injection system in their vehicles as well. Because the fuel is sprayed right into the engine, it offers high levels of power and efficiency, which is ideal for performance vehicles.