Automotive fuel injectors seem to be all the same but they differ in shape, size, and capacity to flow fuel.
The most common injector is the top-feed type. There are o-ring injectors that are usually inserted in a metallic or plastic fuel rail. Another kind is the rubber-hose injector.
In this type of injector, a rubber hose is directly attached to the injector inlet.
There is basically two type of side-feed injectors. The first type of injector is used in MPFI (Multi-Port Fuel-Injection) systems. This injector fits inside the fuel rail. The second is used in TBI (Throttle-Body Injection) systems and usually, fits inside an injector pod. TBI systems are usually confused with electronic carburetors.
This is not the case. TBI are full-electronic EFI (Electronic Fuel-Injection) systems. They use injectors as opposed to carburetors that rely on pressure differential, venturi, jets, metering rods, power valves, chokes, floats, etc.
TBI EFI uses none of these. The only similarity is that fuel is discharged, and travels through the intake manifold.
Direct fuel-injection is a fuel-injection technology that allows gasoline engines to use fuel more efficiently, resulting in higher power levels, cleaner emissions, and increased fuel economy. Having the right fuel injector cleaner review can save you a lot of headaches when going to the mechanic.
In a common MPFI system (whether batch or sequential fire) fuel is sprayed towards the intake valve in the cylinder head ports. This results in a more precise fuel metering compared with the previous TBI setup.
Direct-Fuel-Injection goes a step further by placing the injector directly in the combustion chamber, just like a spark-plug. Gone are the days of 43psi of fuel pressure since a direct fuel-injection system uses pressures as high as 2500psi. This high fuel pressure is necessary to overcome internal cylinder pressure in systems that meters fuel during the compression stroke (very similar to a diesel engine).
In fact, this type of fuel injection mimics the intake stroke of a Diesel engine thus the 30% advantage in fuel economy compared to similar displacement gasoline engines.
This type of injection is known as a stratified injection, where some amounts of fuel are injected during the compression stroke achieving super lean ratios of 69:1 and an increase in fuel-economy up 30% higher compared to a traditional sequential-fire fuel-injection system.
Now you know the basic and most common type of automotive fuel injectors. In future articles, I’ll talk about injector service and maintenance ranging from basic flush to ultrasonic cleaning.
Stay tuned for more about fuel injectors! Place your comments and happy wrenching!