legenddriver
New Member
about emmisions!!!!!
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ok guys i see alot of people on here having problems passing emmisions testing so here is some info that might help also sorry if this is in the wrong section but i figured this was pretty close to a how to or what to look for any way.
HC
first HC's are hydrocarbons which is unburend fuel. if your getting high HC readings the most likly casue is a missfire so check for bad plugs, wires, cap, rotor, weak coil, or damaged coil, or over advanced timing. other causes can be low compression, worn rings, burned valves, and blown head gaskets. high HC leavels will cause O2 to go up which wil cause the computer to think that you have a lean mixture so the computer will just pump more and more fuel which will lead to cat failure. o yeah and a sticking egr valve can also have an effect on this
CO
CO is carbon monoxide. high co is a rich mixture that can be caused by high fuel pressure due to bad fuel pressure regulator. it can also be caused by leaky injectors, thermostat stuck open( so dont go pulling your thermostats out thinking your gonna get more hp you will just loose power and fuel milage) or it can also be caused by a pluged air filter. other causes are saturated charcoal canister, faulty purge valve on the canister, fuel saturated crankcase due to infrequent oil changes or short trip driving. if CO goes up so will HC and visa versa.
NOX
NOX is nitrogen Oxid. NOX is caused by an increase in combustion chamber temperature. which could be from low oil level, over advansed timing, and higher then normal compression. also could be a cooling system malfunction like faulty cooling fan, leanking hoses, bad thermostat, or a plugged radiator. also can be from wrong or low octane fuel, bad egr, vacuum leaks, low fuel pressure, wrong spark plug heat rang, or bad catalytic converter. but if you have really high NOX your HC and CO levels will be low most places that i know of dont pay much attention to high NOX on vehicles older then like 94 or 95. also NOX highest levels will be when you have a stoichiometric air fuel ratio. that just means your air fuel is right where it should be at 14.7:1.
also if your cat is bad check all these things i have listed cuz a cat should not go bad ever unless there is a problem some where else. dont replace the cat untile you figure out what caused it to go bad cuz the cat should last the life of the vehicle. if you replace it without finding and fixing what caused it to go bad it will just go bad again and good cats arent cheap.
hope this helps some people out. also if you guys still have problems or arent passing for diffrent reasons or at serten rpms and load ranges let me know cuz i can help you on were to look for problems at
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ok guys i see alot of people on here having problems passing emmisions testing so here is some info that might help also sorry if this is in the wrong section but i figured this was pretty close to a how to or what to look for any way.
HC
first HC's are hydrocarbons which is unburend fuel. if your getting high HC readings the most likly casue is a missfire so check for bad plugs, wires, cap, rotor, weak coil, or damaged coil, or over advanced timing. other causes can be low compression, worn rings, burned valves, and blown head gaskets. high HC leavels will cause O2 to go up which wil cause the computer to think that you have a lean mixture so the computer will just pump more and more fuel which will lead to cat failure. o yeah and a sticking egr valve can also have an effect on this
CO
CO is carbon monoxide. high co is a rich mixture that can be caused by high fuel pressure due to bad fuel pressure regulator. it can also be caused by leaky injectors, thermostat stuck open( so dont go pulling your thermostats out thinking your gonna get more hp you will just loose power and fuel milage) or it can also be caused by a pluged air filter. other causes are saturated charcoal canister, faulty purge valve on the canister, fuel saturated crankcase due to infrequent oil changes or short trip driving. if CO goes up so will HC and visa versa.
NOX
NOX is nitrogen Oxid. NOX is caused by an increase in combustion chamber temperature. which could be from low oil level, over advansed timing, and higher then normal compression. also could be a cooling system malfunction like faulty cooling fan, leanking hoses, bad thermostat, or a plugged radiator. also can be from wrong or low octane fuel, bad egr, vacuum leaks, low fuel pressure, wrong spark plug heat rang, or bad catalytic converter. but if you have really high NOX your HC and CO levels will be low most places that i know of dont pay much attention to high NOX on vehicles older then like 94 or 95. also NOX highest levels will be when you have a stoichiometric air fuel ratio. that just means your air fuel is right where it should be at 14.7:1.
also if your cat is bad check all these things i have listed cuz a cat should not go bad ever unless there is a problem some where else. dont replace the cat untile you figure out what caused it to go bad cuz the cat should last the life of the vehicle. if you replace it without finding and fixing what caused it to go bad it will just go bad again and good cats arent cheap.
hope this helps some people out. also if you guys still have problems or arent passing for diffrent reasons or at serten rpms and load ranges let me know cuz i can help you on were to look for problems at