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How Does it Work /
Black Smoke
Black Smoke
Black smoke is caused by too much fuel being processed inside your car's engine
and then released from the tailpipe of your car. Malfunctions in fuel delivery or
internal system leaks will cause
black smoke
to come from the tailpipe. Before fuel injection became available in automobiles in the mid 1980's, the
carburetor was the main fuel and air mixer in most vehicles. A carburetor was a
simple device that supplied the engine with proper fuel to air mixtures. Carburetors
performed two operations 1. meter air flow 2. deliver the correct amount of
fuel to air mixture. This mix could be kept even during the wide range of extra
factors associated with an engine such as high temperature, cold starting, hot starting,
idling and acceleration.
Fuel Injector Cut Away
The primary difference between a carburetor and a fuel injection system is that
the fuel injection system atomizes fuel by pushing it through a small nozzle under
pressure, while a carburetor utilizes vacuum created by air flow into the intake
manifold. Airflow in an injection engine is controlled by the throttle body; fuel
is distributed directly in each cylinder. This creates better fuel control, lower
emissions and faster acceleration. The process of measuring the amount of fuel a
fuel injector is dispersing is determined by the ECM (engine control module). The
fuel injection system has several parts: the mass airflow sensor or map sensor,
throttle body, throttle position sensor, idle control valve, fuel pump, fuel pressure
regulator, fuel lines, and oxygen sensors.
Cause of Black Smoke
Black smoke is caused when the mix of fuel and air becomes un-balanced. Normal
mixture is 14.5 parts air to1 part fuel. When the fuel to air mixtures change because
of a malfunction the mixture can go as high as 14.5 to 2 or 3, two to three times
the proper amount. The
black smoke is the excess fuel generated from the rich mixture and can be cause
by one of the following:
- Plugged Air Filter
- Shorted or stuck fuel injector
- Failed fuel pressure regulator
- Vacuum leak
- Shorted ECM Sensor
Trouble Shoot
Black Smoke
Check Engine Light
If the check
engine light is illuminated the PCM has detected a malfunction that could be
causing the problem,
scan the PCM
to retrieve
trouble codes and repair as needed.
Preventive Maintenance
To check your car's mixture you will need to use a gas analyzer to test your
exhaust gases. This will measure the carbon monoxide, hydrocarbon, nitrogen
oxide and oxygen content
of your exhaust. During a normal
smog inspection the fuel/air mixture is tested and a report generated. When
a tune up is performed the spark plug end insulator can tell you whether you have
a lean or rich mixture. Brownish grey is the desired color and confirms proper mixture.
Black and sooty means the mixture is too rich while white to light grey confirms
a lean mixture.
Fuel injection systems rely on pressurized fuel to operate. Maintaining this pressure
is mandatory for the system to function properly. Replace your
fuel filter with every
tune
up to keep your injection system operating properly.
How Does it Work
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Smoke
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Smoke Questions and Answers
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