How Fuel Injection Systems Have Improved Over the Years
Fuel economy continues to be a big push for automobile makers as they strive to meet the stringent Corporate Average Fuel Economy (CAFE) standards we’ve discussed in previous articles. In this post, we’ll cover a brief history of fuel delivery to the engine, and go over the new technology of gasoline direct injection (GDI), also referred to as direct fuel injection (DFI), versus multi point (or multiport) fuel injection (MPFI).
When gasoline-driven cars were first manufactured, a carburetor was used to mix a tiny amount of fuel (about 10 milligrams) with the right amount of air before sending the mixture into the engine’s combustion cycle. This process was not always consistent as cars could run too rich (smoky, stalled easily, and the engine would flood) or run too lean (not have enough explosive power to run at all with potential engine damage). This was not very fuel efficient or emissions-friendly.
Due to the ever-improving technology of cars, carburetors were phased out in the late 80’s and replaced with Fuel Injection Systems. The first to be widely used was throttle body injection (TBI). This was also referred to as single point injection. Due to progress and varying issues, manufacturers came to favor the multipoint fuel injection systems instead.
MPFI systems use separate injector ports to spray fuel into each cylinder. There’s central port injection, which some say looks like a spider injector. This system releases fuel at the same time into all the valves which means some of the cylinders have time for the fuel to condense and not com-bust as readily. They updated that system with sequential fuel injection which solved that problem, and it’s the most common fuel metering system in gas-powered cars today.
The gasoline direct injection (GDI) is a more advanced version of the multipoint system, and has been around since 1925 (invented by Swedish engineer Jonas Hesselman). The difference with this system, versus the MPFI, is that instead of using an intake port to deliver the fuel, GDI injects fuel directly into the combustion chamber of each cylinder. This type of system provides cleaner emission, increased fuel economy, and more energy in the engine. Although that all sounds great, it comes at a premium price.
Cars that run on an MPFI system are going to generally cost less than a vehicle with the newer GDI technology. This is because the newer systems are more costly to produce because of all the other necessary components the system needs to function. GDI systems need specially designed catalytic converters to handle the emissions after recirculating the exhaust, yet it’s still prone to carbon build-up that has been known to break off and cause further issues.
High-pressure fuel pumps also appear to be an early failure point in cars using GDI, usually due to a low-pressure pump failing to work properly. Sturdier injectors are also needed because of the extreme exposure to the heat and pressure of the combustion chamber. Normal fuel injectors spray out gasoline at about 40 to 60 pounds per square inch (PSI), but direct injectors have to spray the fuel at over 2,000 PSI. When problems occur, professional-level service is needed to diagnose the original problem in order for the repair to be successful. This is one of the reasons why these vehicles not only cost more, but are also more expensive to maintain and repair.
As technology advances, vehicles with GDI should become easier and more affordable to manufacture. For now, no matter what you drive, Kwik Kar can make sure your fuel system stays in good working order. If you have questions about your fuel injection system, fuel cleaners, or anything else regarding your vehicle, please stop by and ask. We are here with answers to help you both on and off the road!
