How an Engine Emission Control System Works
Emission control systems have been incorporated into automobiles to prevent pollution
by limiting the amount of partially burned and evaporated gases into the atmosphere.
These systems have been efficient in reducing the pollution caused by automobiles
to a large extent. Automobiles were first manufactured with
exhaust emissions control systems
in 1966. Since then technology has undergone several changes that has increased
the number of cars which use this technology. The emission released is calculated
by quantity released per distance traveled. The types of emissions are tailpipe
emissions, life cycle emissions and evaporative fuel emissions.
Catalytic Converter The catalytic converter was developed in the early 70's when severe air pollution was emanate, but wasn't made mandatory by the US government until 1976. The catalytic converter or "cat" for short is one of your vehicles main emission control devices. The name was derived from the operation the catalytic converter performs, it takes a catalyst and converts the unburned gasses to burned gases, "catalytic converter".
EGR Valve
An EGR valve is used is to lower KNOX (NO2) gases which occur when the combustion chamber when temperature reaches over 3,500 degrees Fahrenheit. KNOX gases have proven to cause brain damage and have been mandatory on most vehicles since 1976. An EGR (exhaust gas re-circulation) this valve controls exhaust gases to enter the intake manifold and flow into the combustion chamber at certain times in the operation of the vehicle. To test your EGR valve remove the vacuum line that is connected to the valve, apply vacuum using a vacuum pump to the valve while the engine is running. If the engine stalls the EGR system is working, if not, the EGR valve may have failed. Tailpipe emissions are released as bi-products of spent fuel that is combusted inside the cylinders of the engine. These omitted gases consist of carbon monoxide, hydrocarbons, carbon dioxide and nitrogen oxides. To control tailpipe emissions measures have been taken to increasing engine efficiency. This efficiency involves technologies such as lightweight vehicle design, regenerative braking, decreased rolling resistance, increased ignition voltage, minimizing air resistance and improving power train efficiency. Lifecycle emissions are products which are released during the manufacturing, maintenance and disposal of the vehicle. The products include volatile solvents such as auto paint and lubricants, manufacturing plant power waste, oil filter and oil changes, heavy metals, tires, landfills, etc. These kinds of emissions are responsible for creating urban smog which consists of heavy molecular gases which pollute our environment. Temperature change can result in the evaporation of fuel in the tank because of the development of pressure, this is known as gas tank venting. Recently fuel systems have been equipped with a closed system called EVAP, this allows the vapor to be stored in a charcoal canister until it can condense into a liquid and then returned to the fuel tank. Another emission control system known as the air injection reactor or AIR, oxygen is injected in the exhaust manifold. This system decreases the bi-products of incomplete fuel consumption. If the emission control system malfunctions the "check engine" light will illuminate. Scan the PCM for trouble codes, repair the problem, then clear codes to re-test system. Most automobile's have an emission system information label under the hood, or consult a repair manual. The emission system performs regular test while the car is in use called a "test cycle". Tailpipe emission are measured in parts per million or PPM. Presently, the limit for evaporated gases is two grams of HC per hour, which is about one liter per month. At first, the idle test, which was a two-speed test was conducted in the 1980s. Then it was substituted by the dynamometer test in the late 90's, in the accelerated simulated mode or ASM three gases are tested. Various states and countries have developed unique laws about pollution testing of vehicles. If further technical assistance is needed, our certified car repair technicians are ready to answer your car questions. Related Car Repair Information
Catalytic Converter The catalytic converter was developed in the early 70's when severe air pollution was emanate, but wasn't made mandatory by the US government until 1976. The catalytic converter or "cat" for short is one of your vehicles main emission control devices. The name was derived from the operation the catalytic converter performs, it takes a catalyst and converts the unburned gasses to burned gases, "catalytic converter".
EGR Valve
An EGR valve is used is to lower KNOX (NO2) gases which occur when the combustion chamber when temperature reaches over 3,500 degrees Fahrenheit. KNOX gases have proven to cause brain damage and have been mandatory on most vehicles since 1976. An EGR (exhaust gas re-circulation) this valve controls exhaust gases to enter the intake manifold and flow into the combustion chamber at certain times in the operation of the vehicle. To test your EGR valve remove the vacuum line that is connected to the valve, apply vacuum using a vacuum pump to the valve while the engine is running. If the engine stalls the EGR system is working, if not, the EGR valve may have failed. Tailpipe emissions are released as bi-products of spent fuel that is combusted inside the cylinders of the engine. These omitted gases consist of carbon monoxide, hydrocarbons, carbon dioxide and nitrogen oxides. To control tailpipe emissions measures have been taken to increasing engine efficiency. This efficiency involves technologies such as lightweight vehicle design, regenerative braking, decreased rolling resistance, increased ignition voltage, minimizing air resistance and improving power train efficiency. Lifecycle emissions are products which are released during the manufacturing, maintenance and disposal of the vehicle. The products include volatile solvents such as auto paint and lubricants, manufacturing plant power waste, oil filter and oil changes, heavy metals, tires, landfills, etc. These kinds of emissions are responsible for creating urban smog which consists of heavy molecular gases which pollute our environment. Temperature change can result in the evaporation of fuel in the tank because of the development of pressure, this is known as gas tank venting. Recently fuel systems have been equipped with a closed system called EVAP, this allows the vapor to be stored in a charcoal canister until it can condense into a liquid and then returned to the fuel tank. Another emission control system known as the air injection reactor or AIR, oxygen is injected in the exhaust manifold. This system decreases the bi-products of incomplete fuel consumption. If the emission control system malfunctions the "check engine" light will illuminate. Scan the PCM for trouble codes, repair the problem, then clear codes to re-test system. Most automobile's have an emission system information label under the hood, or consult a repair manual. The emission system performs regular test while the car is in use called a "test cycle". Tailpipe emission are measured in parts per million or PPM. Presently, the limit for evaporated gases is two grams of HC per hour, which is about one liter per month. At first, the idle test, which was a two-speed test was conducted in the 1980s. Then it was substituted by the dynamometer test in the late 90's, in the accelerated simulated mode or ASM three gases are tested. Various states and countries have developed unique laws about pollution testing of vehicles. If further technical assistance is needed, our certified car repair technicians are ready to answer your car questions. Related Car Repair Information
- Emissions Questions
- How to Test a Catalytic Converter
- How to Replace an EGR Valve
- How to Scan for Trouble Codes
- How to Replace an Oxygen Sensor
- How to Test an Oxygen Sensor