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Emissions Air is made up of 21 O2 78 N 1 other gasses mostly argon Fuel is primarily made up of HC Perfect combustion HC O2 N2 in Heat H2O CO2 and N2 out Imperfect combustion Adds HC CO NOx and O2 to exhaust Stoichiometric Much of our emissions are related directly to A F mixtures Theoretical best a f ratio for emissions economy performance is 14 7 1 14 7 pounds of air to 1 pound of fuel Think about it Gasoline weighs 6 pounds per gallon Air weighs 1 pound per 100 gallons At 15 1 it takes 9000 gallons of air to burn 1 gallon of fuel 9000 Gallons of air is equal to a single car garage HC Hydrocarbons Unburned fuel Currently measured in parts per million ppm Common causes of high HC Missfiring will cause HCs Ignition Mechanical Lean A f ratios off either way Timing too advanced Cools exhaust and cylinder walls Not so common causes of HC Quench areas in combustion chamber Carbon Poor combustion chamber design Cam profiles too aggressive CO Carbon monoxide Currently measured in EXTREMELY deadly gas Partially burned fuel Too much fuel or too little O2 Combustion process ran out of air CO directly related to a f ratios Causes of high CO Hard to use as an A F guide over 15 1 due to flattening out of curve Must use O2 above stoichiometric O2 Oxygen Currently measured in Unused air in exhaust O2 directly related to A F Can also come from dilution Air pump exhaust leaks Misfires will raise O2 If O2 is 5 and vehicle running OK then it must be from dilution CO2 Carbon dioxide Currently measured in Byproduct of complete combustion Peak indicates good A F Any problems pull CO2 away from peak Used by Washington State to determine exhaust system integrity NOx Oxides of nitrogen Created when peak combustion temps exceed 2500F Causes of high NOx Advanced timing Inoperative EGR Carbon build up Anything that overheats combustion chamber Smog what is it Ground level ozone O3 Three ingredients HC NOx and sunlight CO is a pollutant all by itself State emissions testing Attainment areas vs

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