Friday, December 23, 2011

Fuel Injection Systems

All gasoline-powered engines require only two basic elements to run - the proper quantity of fuel for any given rpm and throttle opening, and spark from the ignition coil at the right moment. A carburetor's fuel-delivery system is compound of distinct fuel circuits, each with a specific job to comply. During startup of a cold engine, the choke circuit adds supplementary fuel and air to maintain engine from stalling. When the engine reaches operating temperature, the choke circuit shuts down. At idle (as the throttle is opened), the idle mixture from the screw and transfer port circuits allocates extra fuel as needed by the engine. As airflow into the engine raises, the main fuel circuit regulates fuel flow related to the proportion of throttle opening. If the throttle is opened unexpectedly, an accelerator pump circuit squirts fuel straightly into the intake manifold.

Even though carburetors have supplied fuel delivery services for well over one century and have always basically worked pretty well, there are several things they simply can't handle. A carburetor is fundamentally a hunk of aluminum with a number of holes drilled into it. As air pressure within the carburetor changes, fuel and air flow through the diverse holes and into the engine. However, a carburetor's capacity to deal with constantly changing operating environments is restricted with regard to reactions to modifications in altitude and compensation for engine temperature. They also lack accurate fuel control for emissions purposes and produce overall excessive fuel consumption pending steady-state engine operation and acceleration. In brief, carburetors are just too dumb to continue being helpful for providing accurate air/fuel mixtures in present vehicles. What is required is a fuel delivery system with some brains.


Furthermore to performing all the functions of a carburetor, the EFI system also adjusts engine idle speed and numerous ignition system timing functions. It regulates fuel delivery utilizing electromagnetic valves (fuel injectors) that open electronically for different lengths of time. When the fuel injectors are turned on, they disperse fuel into the engine. The quantity of on time is called injector pulse width, and the longer this is, the greater the quantity of fuel injected into the engine. While all EFI systems utilize fuel injectors that operate in the same manner, there are distinct EFI designs and computer strategies in use nowadays.

Throttle body injected engines utilize only one or two injectors situated where the carburetor used to be. Afterward fuel is injected into the throttle body, it goes through an intake manifold before reaching each cylinder.

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