CA Smog failed due to high NOx
#1
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CA Smog failed due to high NOx
I recently failed my smog test in CA. They said that I was fine on everything besides being a couple hundred high on the NOX emissions at 15MPH. What would be the reson for only failing this part of the test? What causes high high NOx emissions. Do those "Gauranteed to pass" thing ever work? THanks for your help.
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If your care is mostly stock, it may be a clogged or disfunctional cat. I had that problem on my car, though i had a catback, intake and ported engine. I replaced me stock cat with a Random Technologies high flow one and i passed smog easily
#5
Racecar - Formula 2000
EGR valve is a possibility
The main function of the EGR valve is to reduce NOX emissions by diluting the fuel-air mixture with burned gasses to reduce the peak temperature reached during combustion (high combustion temps cause excessive NOX). Check to see if it's operating properly.
Dave
Dave
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#9
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heh...we're neighbors, i'm in coto de caza
what was the numbers of your NOx reading?
+1
EGR valve maybe a good posibility, however....there might be a relationship with your o2 sensor and also a bad Cat. (which probably blew out cause of your o2 sensor. have your EGR valve tested. as well as o2 sensor and Cat.
what was the numbers of your NOx reading?
Originally Posted by DaveW
The main function of the EGR valve is to reduce NOX emissions by diluting the fuel-air mixture with burned gasses to reduce the peak temperature reached during combustion (high combustion temps cause excessive NOX). Check to see if it's operating properly.
Dave
Dave
EGR valve maybe a good posibility, however....there might be a relationship with your o2 sensor and also a bad Cat. (which probably blew out cause of your o2 sensor. have your EGR valve tested. as well as o2 sensor and Cat.
#11
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I don't think the EGR is operative at 15mph. High NOX Is usually the result of higher than normal combustion temperatures + excess air (e.g., lean) or some combination of factors. Ignition timing is also a major factor, might want to check it first. Note that the first brick in the main cat is designed to convert NOX, so it could also be a marginal or failed convertor.
#12
Recovering Miataholic
is your air pump working? you won't pass smog in california without it.
If/when replacing the catalytic converter, be careful to choose a brand which does not cut corners on the internal distribution of the secondary air. I bought a Bonez aftermarket cat which returned worse results than the old, bad original. Wound up paying for a new OEM cat, which cured the problem and has been OK for the last 3 tests.
#13
Originally Posted by wstrohm
Wound up paying for a new OEM cat, which cured the problem and has been OK for the last 3 tests.
#14
Recovering Miataholic
Holy crap in a can Batman......how much did that cost you and where did you buy it from?
You can see why I tried an aftermarket cat first (in addition to new plugs, wires, and O2 sensor, none of which passed)!
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Originally Posted by wstrohm
$1265.62 (discounted from $1406.25)+2 gaskets @ 17.72 total. From Heritage Lincoln Mercury Ford Mazda in Huntington Beach, CA. on 08/09/2002.
You can see why I tried an aftermarket cat first (in addition to new plugs, wires, and O2 sensor, none of which passed)!
You can see why I tried an aftermarket cat first (in addition to new plugs, wires, and O2 sensor, none of which passed)!
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