ok guys i see alot of people on here having problems passing emmisions testing so here is some info that might help
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. and if you think your gonna get more power from taking your cat off you wont, but your not gonna really loose it ether its just gonna move you low end torque up in the rpms and we all know we need as much low end power as we can get so we can get these heavy cars moving.
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
Car 1: 1990 Legend LS sedan
Car 2: 2002 Dakota SLT QC
Car 3: 1998 Bandit 1200S
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Quote:
Originally Posted by legenddriver2004
...HC
...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.
High HC indicates a very rich mixture, which means either too much fuel for the available air or too little air for the fuel supplied. I have no idea what you were thinking when you wrote that. High O2 is the opposite condition of what would cause unburned HCs, i.e. lean condition and would appear in your NOx section.
Quote:
Originally Posted by legenddriver2004
NOX
NOX is nitrogen Oxid.
Technically, It's "NOx" and it means "oxides of nitrogen", of which there are several species that result from combustion. NO, NO2, NO3, N2O2, N2O3, etc.
Quote:
Originally Posted by legenddriver2004
...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.
Not so. Highest NOx production happens at about 16:1. I offer "The Internal Combustion Engine in Theory and Practice, Vol #2" by Charles Taylor as my supporting material. He has a really nice graphic that shows the interrelation between fuel mixture and NOx production.
Otherwise, you wrote a comprehensive post. Why not spend a few minutes editing it for spelling, punctuation and capitalization for a really spiffy post.
[edited 30-Sep-06. Finally got my copy of Taylor's book back and checked the NOx graphic I mentioned.]
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2007 Mazda MX-5 Touring
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1998 Suzuki Bandit 1200S w/ $tuff
1994 Nissan Sentra SE-R w/ $tuff converting to ITA
1990 Acura Legend LS sedan leaving the stable
Last edited by slartibartfast; 09-27-06 at 10:37 AM.
yes high HC's could be from a rich mixture but it is most commonly caused by a missfire due to weak ignition and all the preavious things i listed. and i was partly wrong about o2 but o2 will be higher then normal with high HC's. and dude nitrogen Oxid, oxides of nitrogen same thing. im mean come on man! and the highest NOx will be at or just past stoichiometry so 14.7:1-15:1 air fuel ratio, not your 17:1. by 17:1 NOx is falling back off. that is why an egr opens at just off ideal cruising which is when your air fuel is going to be in the 14.7:1-15:1 rang the most plus then you dont really need alot of hp. your just cruising unlike at idle you need all the power the engine is producing and same with WOT your useing all the power the engine can make. o and all my information is from the book "Automotive service" by Tim Gilles. Tim Gilles is a professor at santa barbara city college. he is also a ASE master technician and ASE master Machinist so i know my information is correct. The book is also supported by the ASE certification program and the NATEF. this is the book issued to every UTI student and wyotech student so im sure the information in this book is right. plus im ASE certified in basic engines, electrical fundamentals, and engine performace. engine performace just so happens to include emmision testing and emmision controle devices, so dont come telling me im wrong just cuz you see i have hardly any posts and im only 19. im not trying to be a dick, im just supporting my information i posted. o and i dont really care all that much about speeling, punctuation, and capitalization. im a technician not an english major!
Last edited by legenddriver2004; 08-25-06 at 12:50 AM.
Car 1: 1990 Legend LS sedan
Car 2: 2002 Dakota SLT QC
Car 3: 1998 Bandit 1200S
iTrader Score: 0 reviews
Quote:
Originally Posted by legenddriver2004
...so dont come telling me im wrong just cuz you see i have hardly any posts and im only 19.
Bite me. I called you on it because I think you're wrong on that particular point.
Quote:
Originally Posted by legenddriver2004
im not trying to be a dick, im just supporting my information i posted.
And I heartily applaud that. I work in research and citing sources is a basic part of research writing. Too many people can't or won't.
Quote:
Originally Posted by legenddriver2004
o and i dont really care all that much about speeling, punctuation, and capitalization. im a technician not an english major!
A great technician who can't communicate is not really great. On the great anonymous Intraweb, you're known by two things, and two things only: What you write and how you write it. Your writing sucks. It costs you nothing but a few extra minutes to make a presentable missive that is grammatically correct and easy to read. People appreciate easily read messages when the only way you can communicate is via writing.
__________________
Bruce in Houston
2007 Mazda MX-5 Touring
2002 Dodge Dakota QC tow beast, stock!
1998 Suzuki Bandit 1200S w/ $tuff
1994 Nissan Sentra SE-R w/ $tuff converting to ITA
1990 Acura Legend LS sedan leaving the stable
Car 1: '87L, 5 speed Sedan
Car 2: '71 Datsun PL521
Car 3: '03 Infiniti I35
iTrader Score: 14 reviews
Hey guys relax huh?
Legenddriver2004, slartibartfast was simply throwing in some of his info based on his expiriences and, as you'll learn, he has a bit of a "straight-up" style of communication but means you no harm....its just the internet dude....
Slartibartfast,
The guy did post up some good info and we can all add suggestions, additions, and/or corrections as the thread evolves....so just ease up on the guy he's new here....
And the both of you....we aren't running an Engilsh class here so don't feel like youre going to be judged based on your typing abilities, BUT please do keep in mind that typing, writing, and reading is the main form of communication so please remember that others will be reading what you put, so try and make it as painless as possible huh?
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I just failed emmisions my NOx measured 1640 when the state only allowed 1094 .. I have new thermosat , flust rediator , new plugs , valve cover gasket with splark plungs orings, also I always use 93 octane .. How do I check the EGR valve is the away to clean it or just replace it?
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How do I check the EGR valve is the away to clean it or just replace it?
There is a "full page" on the manual to check the EGR valve system... the other culprit for high Oxides of nitrogen would be your catalytic converter, maybe its time for a new cat.
^^^ No G2 I just notice the thread was G1 sh!t .. so is it different?
oh and pnoye2 the cat is new
Technically whyteLegend... there are NO difference on SMOG testing, though requirements varies from state to state, ie; NOx not required, functional testing on other Emission components are N/A, etc., etc.
As for G1 and G2 Legends are concerned... YES they are not the same, the G2's ECS are more complex than the G1's, its more a PITA sorta thing.
I'd concentrate on the EGR valve system... perhaps cleaning the EGR pipe?
THANKS pnoye2, I cleaned the EGR valve and pipe (clugged very bad nothing was getting through it) with a few bottles of carb cleaner, flat head screw driver & clothes hanger. Took it for free restest and PASSED ... went down 550 points on the NOx ... I also replaced the EGR gasket cost $7.50 retail at the dealer.
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