Combustion 101

A major benefit of fuel injection systems is better control
of toxic exhaust emissions.   Unburnt gasoline
(hydrocarbons) and nitrogen-oxide emissions are toxic for
the environment, anyone who has ever been near the
exhaust of a running car can attest to the unpleasant
odor—not fun to breath.  A fuel injection computer
measures the level of oxygen in the exhaust and calculates
the air fuel ratio.  The ideal ratio, as you may remember, is
14.7 to 1 air to fuel.  If the ratio is higher i.e., more air or
less fuel, it is referred to as “lean”.  

A lean condition can result in high nitrogen-oxide
emissions, low power, engine knocking, even engine
damage.  If the ratio is lower than 14.7 to 1 (less air or
more fuel), the condition is called “rich”.  A rich condition
can result in unburnt hydrocarbon pollution, carbon
deposits on engine parts, clogged passages, and poor fuel
economy.  It falls to the computer to keep the air fuel ratio
as close to 14.7 to 1 as possible UNDER ALL
CONDITIONS- something that is impossible with a
carburetor.  An additional benefit of this on the fly
controllability is fuel economy.  The computers fine tuning
provides the precise amount of fuel needed, and not a
drop more.  Thus waste is minimized, unlike a carburetor
where it’s optimized for one scenario and operates
inefficiently otherwise.  
Fuel Injection
Fuel Injection
Oxygen sensor diagram
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