Emission Controls

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Emission Controls
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Emission Controls

• Before beginning to understand emission controls
  you should know the reason why emission controls
  were installed into the automobile.
• 1. To reduce the amount of pollutants entering
  the atmosphere .

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Emission Controls

• Smog is a term developed from smoke and fog
• Smog is form when airborne pollutants is formed
  with oxygen and other atmospheric gasses to
  produce a grayish yellow smoke. The resulting
  smoke is called photochemical smog.

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Smog

• Smog is can be a major problem in larger cities
  (New York and LA)
• Smog can be harmful to
• A. Humans
• B. Plants
• C. Animals and even effect paint rubber and other
  materials.

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Smog

• One of largest producer of photochemical smog is
  the automotive internal combustion engine.
• The EPA (environmental protection agency) begin
  putting restriction on automotive manufactories
  in the mid 60.

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Motor Vehicle Emissions

• Motor vehicle emission are emission produce by
  motor vehicles. They include
• A. Hydrocarbons (HC)
• Carbon monoxide (CO)
• Oxides of nitrogen (NOx)

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Exhaust Gasses

• Hydrocarbons (HC) are emission of unburned
  petroleum products being released into the
  atmosphere.
• All petroleum products and made of hydrocarbons
  (hydrogen and carbon compounds) this includes
• Gasoline LP-gas.
• Diesel motor oil.

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Exhaust Gasses

• Hydrocarbons are produced because of incomplete
  fuel combustion or fuel evaporation.
• Hydrocarbons emission is considered a hazardous
  form of air pollution because of.
• Eye.
• Throat.
• Lung irritation.
• And possibility cancer.

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Exhaust Gasses

• In north Carolina a vehicle must not exceed 220
  ppm of hydrocarbons emissions.
• High hydrocarbon emission are the results of a
• cylinder misfire.
• Improper ignition timing
• Worn cylinder rings (pumping oil into the
  combustion chamber

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Exhaust Gasses

• Carbon monoxide emission are exhaust emission
  that is the result of partially burned fuel.
• A high carbon monoxide emission can be caused by
  a
• Restricted or dirty air cleaner.
• Advance ignition timing.
• Clogged fuel injectors.

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Exhaust Gasses

• Oxides of nitrogen, (NOx) are emission produced
  by extreme heat.
• Air consist of approximately 79 nitrogen and 21
  oxygen
• When combustion chamber temperature reaches 2500
  degrees F or 1370 degrees C nitrogen and oxygen
  combine to produce oxide of nitrogen (NOx)

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• In North Carolina the standard for Carbon
  Monoxide is 1.2 of the total exhaust output.

Muffler
HC 220 ppm CO 1.2
Exhaust output
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Exhaust Gasses

• Oxides of nitrogen is responsible for the dirty
  brown color is SMOG.
• NOx is a eye and respiratory irritant.
• Newer high compression, learn air fuel mixture
  and hotter running engine produces more NOx than
  earlier engine.

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Exhaust Gasses

• The same factors that increases NOx will tend to
  improve fuel mileage and lower HC and CO2
  production.
• This means that to increase fuel economy and
  lower HC and CO2 production NOx will increase.
• For this reason emission controls have beedn
  added to lower all form of emissions

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Exhaust Gasses
NOx increases
HC increases
Richer
Leaner
14.7 1 AFR
Hc and Co decreases
NOx decreases
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Exhaust Gasses

• Before understanding emission controls we need to
  first understand where they come from.
• Particulates are solid particle of carbon soot
  and fuel additives that blow out the tail pipe.
• Engine crank case blow by. Caused by heating of
  oil and unburned fuel vapors that blow past the
  engine rings.

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Exhaust Gasses

• Fuel vapors different chemicals that enter the
  atmosphere as fuel evaporates.
• Engine exhaust gasses are harmful chemical that
  are produced inside the combustion chamber and
  are blow outr the tail pipe.

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HC CO Solid particulate
Catalytic Converter
Exhaust manifold
Fuel Tank
Air
Fuel Pump
Fuel
Fuel Vapors
Fuel
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Exhaust Gasses

• Automotive manufactures agree the best way to
  lower exhaust emission is to burn all the fuel
  entering the combustion chamber.
• Modern engine have introduced several
  modification to ensure all fuel entering the
  combustion chamber is burned.

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Exhaust Gasses

• Some engine modification are
• Lower compression ratio, by lowering compression
  ratio vehicle can burn unleaded fuel. The use of
  unleaded fuel allows for catalytic converters
  that help reduce HC and CO emissions.
• Lower compression ratio also lower combustion
  temperature reducing NOx emission.

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Exhaust Gasses

• Smaller combustion chambers, allows for more heat
  to remain inside the combustion chamber that can
  aid in the burning of fuel.
• Reduce quench areas, the areas between the piston
  and the cylinder head is the quench area. If this
  areas is to close fuel will not burn completely
  increasing HC and CO emissions. Modern engine are
  design to reduce high quench areas.

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Exhaust Gasses
Quench area
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Exhaust Gasses

• Decrease valve overlap, is used to decrease
  exhaust emission. A larger valve overlap
  increases power but dilutes incoming fuel mixture
  and requires a richer air fuel mixture at lower
  engine speed therefore increasing HC and CO
  emissions.

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Exhaust Gasses

• Overlap

Intake Exhaust
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Exhaust Gasses

• Higher combustion chamber temperature, are used
  to reduce HC and CO emissions.
• Today vehicles used hot thermostats than earlier
  model helping to increase combustion chamber
  temperature.
• Leaner air-fuel mixtures help fuel burn better
  lower HC and CO emissions.
• Wider spark plug gaps, are used to burn the
  leaner fuel mixture and helps prevent spark plug
  fouling.

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Exhaust Gasses
Thermostats are now 190 degrees
Wider spark plug gap Some are .080 thousands
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Learning Quiz

• 1. When is photochemical smog formed?
• A. when airborne pollutants is formed with
  oxygen and other atmospheric gasses
• B. When Oxygen is mixed water inside the
  catalytic converter.
• C. When exhaust gasses is heated to over 2500
  degrees
• D. All the above

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Learning Quiz

• 2. Smog can be harmful to
• A. Humans
• B. Plants
• C. Rubber and medals
• All the above

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Learning Quiz

• 3.Technician A says CO is a hazardous exhaust
  emission. Technician B says HC is a hazardous
  exhaust emission. Who is correct?
• A. Technician A only
• B. Technician B only
• C. Both technician A and B
• D. Neither technician A nor B

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Learning Quiz

• 4. Oxides of Nitrogen is produced when
• A. Combustion chamber temperature is to cold.
• B. Combustion chamber temperature is too hot.
• C. Atmospheric condition is humid.
• D. all the above

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Learning Quiz

• 5. High hydrocarbon are caused by
• A. Cylinder misfire
• B. Dirty air filter
• C. Low fuel pressure
• D. Defective air filter.

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Learning Quiz

• 6. A rich fuel mixture will cause and increase
  in
• A. Hydrocarbons
• B. Oxides of Nitrogen's NOx
• C. Both a and B
• D. Neither A nor B

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Learning Quiz

• 7. In North Carolina the maximum amount of
  Hydrocarbon emission allowed by a vehicle is
• A. 1000 ppm
• B. 1.2 by exhaust volume
• C. 220 ppm
• D. 1 by exhaust volume

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Learning Quiz

• 8. Technician A says Oxides of Nitrogen emission
  increases when combustion chamber temperature
  decreases. Technician B says Hydrocarbon emission
  is the result of a cylinder misfire. Who is
  correct?
• A Technician A only B. Technician B only
• C. A and B D. Neither A nor B

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Learning Quiz

• 9. The best way to decrease exhaust emission is
  to
• A. Increase valve overlap.
• B. Increase compression Ratios.
• C. Increase combustion chamber size.
• D. Burn all fuel enter the combustion chamber.

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Learning Quiz

• 10. Technician A says crankcase blowby is not a
  source of vehicle emission. Technician B says
  modern vehicle have use unleaded fuel to increase
  emissions and allow for the use of catlic
  converters. Who is correct?
• A. Technician A only B. Technician B only
• C. A and B D. Neither A nor B

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Vehicle Emission Control SyEngine Performancestems

• There are several different types of emission
  control system used on modern vehicles.
• Positive crankcase ventilation system (PCV) is
  used to recalculate engine crankcase fumes back
  into the combustion chamber.

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Vehicle Emission Control

• A PCV valve uses manifold vacuum to draw blow-by
  gasses from the engine into the intake manifold
  for reburying by the engine.
• In earlier years automotive manufactories uses
  road draft tubes to remove crankcase blowby
  gasses.

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Vehicle Emission Control

• The uses of road drift tube allowed for blowby
  gasses containing HC, CO, particulates, sulfur
  and small amounts of water to be vented in the
  atmosphere.
• At idle when there is high engine vacuum the PCV
  value is pulled open to remove blow-by gasses
  from inside the engine.

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Vehicle Emission Control

• At part throttle when vacuum is lower a spring
  inside the PCV valve forces the valve partially
  closed. But still allows for some blowby gasses
  to be vented back into the intake manifold for
  burning by the engine.

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Vehicle Emission Control
When engine Vacuum is High PCV valve plunger is
nearly closed
When engine vacuum is low plunger Opens.
Allowing exhaust gasses into Engine.
PCV Plunger
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Typical PCV valve
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Evaporative Emissions Control SystemsEVAP

• The EVAP system prevents Hydrocarbons in the form
  of fuel vapors from entering the atmosphere even
  when the vehicle is not running.
• An EVAP system is considered a closed system.
• Fuel vapor are stored in a charcoal canister when
  the engine is off.

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Evaporative Emissions Control SystemsEVAP

• When the engine is started vacuum pulls fuel
  vapors into the engine fur burning.
• EVAP system different from per emission vehicle
  because no fuel or vapor is vented into the
  atmosphere.

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Unvented Fuel Cap
Rollover Valve
Intake Manifold Vacuum
Charcoal Canister
Fuel Tank
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• A rollover valve is uses to prevent fuel spillage
  in case of a rollover.
• A liquid-vapor separator is sometime used to
  prevent liquid fuel from entering the charcoal
  canister.
• A charcoal canister is used to store fuel vapor
  when the engine is not operating.

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• Most modern vehicles electrically control the
  EVAP system to ensure a cleaner burning engine.
• The EVAP system uses purge lines to connect the
  fuel tank to the charcoal canister and the intake
  manifold.

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12 Volts with engine on
PCM
EVAP Solenoid
Rollover Valve
Fuel Tank
Charcoal Canister
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Enhanced EVAP system

• An enhanced EVAP system has the following
  additional components.
• Fuel tank pressure sensor This sensor monitor
  internal fuel tank pressure
• Canister Vent Solenoid An electrically operated
  solenoid that replaces the Fresh air valve on
  earlier systems
• Service Port is a test point located in the
  engine compartment and is used for testing the
  EVAP system

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Enhanced EVAP system

• A normally open purge solenoid allows fresh air
  to enter the charcoal when in purge mode.
• An enhanced EVAP system requires the uses of a
  bi-directional scan tool for several diagnostic
  procedures.

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12 Volts When ignition is on
EVAP Solenoid
PCM
Engine
Fuel Tank Pressure Sensor
Test port
Rollover Valve
Fuel Tank
Charcoal Canister
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Exhaust Gas Recirculation System (EGR)

• An EGR system has two important jobs
• 1. The recirculation system is used to burn
  un-burns gasses (HC and CO) By recirculation of
  un-burn gasses lower emissions can be achieved.
• 2.By Lowering combustion chamber temperature. By
  lowering combustion chamber temperature NOx
  emission can be lowered.

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Exhaust Gas Recirculation System (EGR)
EGR Control Solenoid PCM Controlled
Vacuum Line
Exhaust Gasses To EGR valve
EGR Valve
Vacuum source
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Vacuum Gauge
Vacuum off throttle
Exhaust Gasses
Exhaust Gasses to Engine
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Exhaust Gas Recirculation System (EGR)

• Later model vehicles use an electronic EGR value.
• The PCM is used to control the flow of vacuum to
  the EGR valve.
• By controlling vacuum to the EGR valve better
  exhaust gas metering can be obtained.

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Electronic EGR Valve
PCM
EGR Solenoid
Intake
Throttle Position Sensor
Vacuum present when Solenoid open by PCM
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Charcoal Canister
EGR Valve
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• To better control EGR flow later model vehicles
  Have begin using digital EGR valves.
• A digital EGR valve is constructed using 3 EGR
  valve and 3 Electrical solenoid

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Top of Digital EGR Valve
PCM
12 from ignition
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Bottom of Digital EGR valve
Ports to Intake manifold
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Emission Quiz

• 1.Two important job or the EGR valve is to
• A. Increases ignition timing and lower
  compression ratio.
• B. Increase HC and CO emissions
• C. Decrease HC emission and increase ignition
  timing.
• D. Recirculation of unburned gasses and lower
  combustion chamber temperature.

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Emission Quiz

• 2.Technician A says that a PCV valve is used to
  remove blow-by from the crankcase. Technician B
  says the PCV valve is used to prevent HC from
  being vented into the atmosphere. Who is
  correct?
• A Both A and B B. Neither A nor B
• C. A only D. B only

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Emission Quiz

• 3. Technician A says that the EGR valve should
  operate at idle with the engine cold. Technician
  A says the EGR flow should increase combustion
  chamber temperature. Who is correct?
• A. Technician A only
• B. Technician B Only
• C. Both A and B
• D. Neither A nor B

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Emission Quiz

• 4.Technician A says lower combustion chamber
  temperature will increase NOx. Technician B says
  increasing combustion chamber temperature will
  lower HC. Who is correct.
• A. Technician A only
• B. Technician B only
• C. Both A and B
• D. Neither A nor B

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Emission Quiz

• 5.Technician A says NOx is not a harmful exhaust
  emission. Technician A says that O2 is not a
  harmful exhaust emission. Who is correct?
• Technician A only
• Technician B only
• Both Technician A and B
• Neither A nor B

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Emission Quiz

• 6. A says a lean misfire can be caused by stuck
  closed EGR valve.
• A. True
• B. False

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Emission Quiz

• 7. Photochemical SMOG is harmful to
• A. Humans
• B. Plants
• C. Rubber and plastic
• D. All the Above

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Emission Quiz

• 8. Technician A says the charcoal canister is
  used to store fuel vapors. Technician B says the
  charcoal canister vents fuel vapor into the
  intake manifold. Who is correct?
• A. Technician A only
• B. Technician B only
• C. Both A and B
• D. Neither A nor B

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Emission Quiz

• 9. Digital EGR valves are controlled.
• A. Mechanically
• B. By the PCM
• C. Both A and B
• D. Neither A nor B

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Emission Quiz

• 10. Technician A says fuel vapor from the fuel
  tank should be vented into the atmosphere.
  Technician B says a defective PCV valve can cause
  engine oil to become diluted. Who is correct?
• A. Technician A only B. Technician B only
• C. Both A and B D. Neither A nor B

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Catalytic Converters

• In the mid 70s automotive manufacture begin
  installing catalytic converters to assist in
  meeting tougher emission standards.
• A Catalytic is a material that can speed-up
  chemical action without changing itself.

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Catalytic Converters

• Automotive catalytic converter are made of
  platinum, palladium and rhodium or a combination
  of these materials.
• Platinum and palladium are used to change HC and
  CO into CO2 and Water.
• Rhodium acts to reduce NOx emissions

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Catalytic Converters

• Due to enhance emissions standard later model
  catalytic converters now use cerium to attract
  and release oxygen inside the converter to aid in
  the process of changing HC and CO to CO2 and H2o

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Catalytic Converters

• The catalyst agent inside a catalytic converter
  is either ceramic beads or a honeycomb-shaped
  blocks.
• All catalytic converters are encased in a
  stainless steal housing.
• NOTE stainless steal is used on newer vehicle
  with catalytic converters because the production
  of water will rust traditional exhaust system
  medals in only a few years

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Catalytic Converters
Catalytic Converter
CO2 H2o
HC and CO
Engine
Exhaust Flow from engine through converter
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Catalytic Converters

• Stainless steal catalytic converter housing are
  design to resist heat.
• Before the catalytic converter can operate an
  operating temperature of around 300 degrees F
  must be reached.

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Catalytic Converters

• This is a honey-comb block type catalytic
  converter.
• Exhaust gasses flow thru the honey-comb block

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Catalytic Converters

• There are a few different types catalytic
  converters.
• Monolithic Converter
• Two way converter
• Three way converter
• Dual bed converter

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Catalytic Converters

• Monolithic converter uses a ceramic honey-comb
  catalytic
• Small ceramic beads converter are referred to as
  a pellet type catalytic converter

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Catalytic Converters

• Two way catalytic converters only convert HC and
  CO
• With a two way converter NOx is not converted
• Two way converter are coated with platinum only
• Two way converter are sometime referred to as
  oxidation converters

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Catalytic Converters

• Three way catalytic converters can convert all
  three exhaust gasses
• HC
• CO
• NOx

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Catalytic Converters

• A three way catalytic converter is usually plated
  with rhodium and platinum
• Three way converter are also called reduction
  converters.

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Catalytic Converters

• Dual bed catalytic converter is an oxidation and
  reduction converter built into one unit.

CO, HC and NOx
CO2 and H20
Mixing Chamber
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Catalytic Converters

• Dual bed catalytic converters must be at an
  operating temperature of 130 degrees F
• When the engine is cold additional air is forced
  into the exhaust manifold to aid in the burning
  and reduction of HC and CO

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Catalytic Converters

• On a warn engine air is forced into the converter
  to aid in burning exhaust gasses.
• As exhaust gasses flows iinto the front part of
  the converter HC,CO and NOx is reduced.
• As exhaust flow into the mixing chamber
  additional air is added to continue the burning
  process.
• Exhaust gasses is the passed into the rear part
  of the converter to reduce HC,CO2 and NOx ever
  more.