Chevrolet TrailBlazer, Service Manual

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Although ozone at ground level can be harmful, ozone is beneficial to the earth's
inhabitants. By having a concentrated ozone layer called the "ozonosphere,'' between 10
and 20 miles (16 - 32 km) up in the atmosphere, much of the ultra violet radiation from the
sun's rays are absorbed and screened. If this ozone layer were not present, much of the
earth's surface would be burned, dried and unfit for human life.
Oxides of Sulfur
Oxides of sulfur (SO
x
) were initially ignored in the exhaust system emissions, since the
sulfur content of gasoline as a fuel is less than 1/10 of 1 percent. Because of this small
amount, it was felt that it contributed very little to the overall pollution problem. However,
because of the difficulty in solving the sulfur emissions in industrial pollution and the
introduction of catalytic converters to automobile exhaust systems, a change was
mandated. The automobile exhaust system, when equipped with a catalytic converter,
changes the sulfur dioxide (SO
2
) into sulfur trioxide (SO
3
).
When this combines with water vapors (H
2
O), a sulfuric acid mist (H
2
SO
4
) is formed and is
a very difficult pollutant to handle since it is extremely corrosive. This sulfuric acid mist that
is formed, is the same mist that rises from the vents of an automobile battery when an
active chemical reaction takes place within the battery cells.
When a large concentration of vehicles equipped with catalytic converters are operating in
an area, this acid mist may rise and be distributed over a large ground area causing land,
plant, crop, paint, and building damage.
Particulate Matter
A certain amount of particulate matter is present in the burning of any fuel, with carbon
constituting the largest percentage of the particulates. In gasoline, the remaining
particulates are the burned remains of the various other compounds used in its
manufacture. When a gasoline engine is in good internal condition, the particulate
emissions are low but as the engine wear internally, the particulate emissions increase. By
visually inspecting the tail pipe emissions, a determination can be made as to where an
engine defect may exist. An engine with light gray or blue smoke emitting from the tail pipe
normally indicates an increase in the oil consumption through burning due to internal
engine wear. Black smoke would indicate a defective fuel delivery system, causing the
engine to operate in a rich mode. Regardless of the color of the smoke, the internal part of
the engine or the fuel delivery system should be repaired to prevent excess particulate
emissions.
Diesel and turbine engines emit a darkened plume of smoke from the exhaust system
because of the type of fuel used. Emission control regulations are mandated for this type
of emission and more stringent measures are being used to prevent excess emission of
the particulate matter. Electronic components are being introduced to control the injection
of the fuel at precisely the proper time of piston travel, to achieve the optimum in fuel
ignition and fuel usage. Other particulate after-burning components are being tested to
achieve a cleaner emission.
Good grades of engine lubricating oils should be used, which meet the manufacturer’s
specification. Cut-rate oils can contribute to the particulate emission problem because of