Dr.
Graham Edgar developed the octane rating system in 1926 to measure
the ability of a fuel to burn cleanly. Higher-octane gasoline burns
in a way that pushes the piston down smoothly during the power
stroke. Lower-octane fuel burns too rapidly, and that can make a
knocking or pinging sound in the cylinder, which can harm the engine.
You maximize fuel economy and get the cleanest emissions by using the
octane rating recommended in your car's owner manual. Eighty-seven and 90 are the
normal ratings for everyday unleaded gasoline
Unfortunately,
misinformed car owners often switch to higher-octane gas in an
attempt to rid their car of foul-smelling exhaust fumes or as a
"treat" for the engine. Don't
be fooled!
When
you refuel with a gasoline rated higher than your vehicle requires,
you are wasting your money and sending unburned fuel into the
emissions system, damaging key components and risking more rotten-egg smells.
Fuel Injection
Fuel injectors controls the
flow of fuel to the pistons.
Vehicles before 1990, this
procedure was carried out by the carburetors, which had changed very
little through the decades. All engines used the same principles. As
fuel regulations tightened, requiring greater fuel efficiency and
cleaner burning fuel, new ways had to be found to meet the more
stringent standards.
Starting
in the late 1970s, a few cars used fuel-injection systems. And all
were making the move to computer control. Around the mid-1980s, the
last of the computer-controlled carburetors were phased out, and
manufacturers shifted to electronic fuel injection on all vehicles.
These early fuel-injection
systems provided an air/fuel mixture much the way a carburetor did.
It was a similar system in that fuel was atomized into one
carburetor-like opening and was called a "central fuel-injection
system" (or a "throttle-body system"). One
significant difference between these early fuel-injection systems and
a carburetor system was that the fuel injector no longer relied on
engine vacuum to pull fuel into the air stream and suck it into the engine.
Fuel injectors inject fuel
under pressure. And in the process a finer atomization (mist)
is produced, hence better fuel burn, more complete combustion,
reduced emissions, and greater economy. Coupled with catalytic
converters, early electronic fuel injectors were efficient enough to
meet EPA emissions regulations during the 1980s.
As emissions standards
tightened again in the 199Os, newer, superior fuel-delivery systems
were required, and in the process cars took another step forward in
engine efficiency. The newer systems were called multiport injection
systems. These systems place an injector on each cylinder, meaning
fuel is directly injected into the cylinder, yielding a finer spray
of fuel, more complete combustion, reduced emissions, and greater economy.
Recall what you now know
about the internal combustion engine.
With the carburetor system,
when the air intake valve opens, the downward moving piston draws in
the air/fuel mixture from the carburetor. The same held true with
throttle-body injection. But with multiport injection, a fuel
injector sits next to the intake valve of each cylinder. On the
downward movement of the piston, only air enters through the intake
valve. The atomized fuel is injected separately into the space
created by the piston's downward motion.
The objective of this Web Page is to familiarize you with basic auto maintenance
- in some common emergencies - not to make you an expert in auto mechanics
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I am in no way, shape,
or form telling you to do this yourself. Your results may vary. If
something goes wrong, it is not my fault! These are just guidelines.
