subject: Auto Parts - Fuel Injection Systems [print this page] In the attempt to keep up with fuel and emissions standards, the fuel systems that are currently used in the modern car has changed totally over the years. In fact the last car sold in the United States to actually have a carburetor was the 1990 Subaru Justy. Since that time, all new cars work with fuel injection.
Although the fuel injection systems have been around since the 1950s they were not used often until wide use in European vehicles began in 1980. Currently, all cars sold in the US have fuel injection systems in their inventory of auto parts.
Fuel Injection Systems
The internal combustion engine for most of its existence had been supplied with fuel by the carburetor and on smaller engines it still is. But with car engines becoming more and more complex to meet emissions requirements that had become stricter and stricter, the catalytic converter was introduced. But this auto part needed very close control of the air-to-fuel ratio in order to work effectively. O2 sensors or oxygen sensors were put in to observe the oxygen amount in the exhaust and another auto part called the "engine control unit" would then take this information making any real-time adjustments to the air-to-fuel ratio. But this system did not maintain control of the carburetor properly as the O2 sensors often needed replacing nor did electrically controlled carburetors so another means had to be developed to manage this problem. This was when the fuel injection systems began to be used in cars.
At the start, single point injection systems replaced the carburetors. But slowly as new and more powerful engines were developed, single point was replaced by "multi-port" injection.
In these systems each cylinder has an individual fuel injector that sprays fuel
right on the intake point and these systems offer much more precise fuel
metering and fuel reaction.
How Do These Systems and Parts Work?
When the gas pedal in the car is pushed this causes the "throttle valve" that it is connected to, to open allowing air in. The ECU notices that the throttle valve is open and increases the rate of fuel to be mixed with the air. This air and fuel in respective amounts need to reach the cylinders at the same time so that there is no hesitation or stalling when the engine begins to work.
O2 sensors observe the air amount going into the engine, and also the oxygen amount leaving the car with the exhaust. With this information the ECU constantly fine-tunes the fuel delivery so that the air-to-fuel ratio is continually correct.
Fuel Injectors
Fuel injectors are really just valves that are electronically controlled and supplied with pressurized fuel by the car's fuel pump. When each injector is energized a plunger will open the valve letting the fuel that is pressurized squirt out in a fine mist through a tiny nozzle into the cylinder.
The fuel amount that is supplied to the engine is managed by how long the fuel injector is opened and this is controlled by the ECU. So that the correct amount of fuel for every operating condition is maintained, the ECU has to monitor the fuel with 8 different sensors all named differently and placed in different areas of the engine.
This is just a very basic attempt to explain how fuel injector systems work and how the auto industry got to this point. As you can see with all these auto parts there are many areas where these systems can fail and new parts need to be ordered. And this is where the internet comes in - as there are many stores online that sell auto parts at good prices.
by: Kurt Ross
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