Emissions
Control Systems
Emission Control Systems
February 18, 2006
Emission control system is a catch-all term that includes
those pieces and parts of your vehicle that are responsible
for reducing air pollution.
Clean air is the target of municipal authorities around
the country and, no big surprise; engines that consume
petroleum are at the heart of the problem. As a result,
emission standards are in place which require specialized
equipment in order to help insure clean air.
Emission pollutants arise from mainly three sources;
crankcase emissions; evaporative emissions and tailpipe
exhaust emissions. Crankcase emissions consist of unburned
fuel and combustion byproducts. These gases are recirculated
back into the engine for reburning by the Positive Crankcase
Ventilation (PCV) valve…an emissions control device
that routes unburned crankcase blowby gases back into
the intake manifold where they can be reburned. The PCV
system is one of the oldest and most valuable emission
control devices. In addition to stopping crankcase emissions
(and thus reducing air pollution), the PCV valve moves
air through the crankcase which helps eliminate moisture
- a leading contributor to sludge. Thus the PCV valve
extends the life of the oil and engine. The PCV valve
requires very little maintenance…the valve and
filter should be replaced somewhere around 30,000 to
50,000 miles (check your owner’s manual for service
intervals).
Evaporative emissions are the fuel vapors that seep out
of the fuel tank and carburetor. They are prevented from
escaping into the atmosphere by sealing the fuel system
and storing the vapors in a vapor canister for later
reburning.
Tailpipe exhaust emissions consist of carbon monoxide
(CO), unburned hydrocarbons (HC) and oxides of nitrogen
(NOX). To a degree, these pollutants are minimized by
various engine design features, careful control of fuel
calibration and ignition timing, and the EGR or exhaust
gas recalculation system.
Frequently we determine that carbon is building up in
the intake manifold and thus blocking the EGR valve.
Unfortunately gasoline additives are not capable of removing
the buildup. The only way we know to clean this is by
removing the manifold and mechanically scraping the carbon
out.
The pollutants that make it into the exhaust are “reburned” by
the catalytic converter before they exit the tailpipe.
If you ever watch your vehicle go through its annual
safety inspection, you’re familiar with the gas
cap pressure check. This test determines the ability
of your gas cap to keep fuel vapors in your tank rather
than let them escape into the atmosphere.
The emission control system is an integral part of the
engine, and should not be tampered with or disconnected.
This is especially true on vehicles with computerized
engine controls and/or those required to pass emissions
testing.
In summary, failure to maintain emission control systems
has several drawbacks:
• It darkens the Dallas skyline, contributes to air pollution
and aggravates respiratory problems.
• It degrades your vehicle’s performance and in
some cases can leave you stranded.
• It can cause you to fail your annual vehicle inspection.
So for clean air, easy breathing, new car performance
and a passing safety inspection grade, regular testing
of your emissions control system is a must.
At Dallas Auto Sports, we have the tools and experience
to keep your system in compliance with local and state
standards. For an appointment call 214.320.2228.
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