I had my car smogged last friday and failed due to
high nox. The day before i had a new carsound cat installed,
changed my spark plugs, and changed my oil.
I have a 95' integra ls w/119000 and AEM intake and
DC headers. My readings were MAX:711
My measure: 891
I passed the other catagories. Would having a bad o2 sensor
have a huge effect for high nox readings?

 

ttt

 

bump. need some advice

 

Are you sure the cat you installed is a three way cat? If it isn't, that will send your NOx readings way up. Also, a lazy O2 sensor will increase NOx readings as well.

 

You said it a carsound cat? If you are driving a 95 Integra that should be OBDII. Car sound does not make a OBDII cert cat converter. I know its not CARB leagal. Chances are its not a 3 way cat.

 

mine is obd1. i dont know if the cat is a three way cat.

 

High Nox is from high combustion temps. Make sure you arent running extremely lean as this would cause high NoX. Good luck!!

 

High Nox can also be caused by exhaust leaks especially closer to the engine than the muffler. Itll also help clean it a little so if you find one and fix it expect the other values to rise a little.

 

im not really that technical about cars. how would
i know if im running lean?

 

You dont have the mods needed to run lean. So dont worry about it. The spark plugs would be very white still.

 

Did you get your engine nice and hot(warm) before you went to the smog test? If not, this could be your reason... Drive around town in first and second gear pulling to 5-6k before shifting to warm up everything. Also, we fixed an '91 Integra two weeks ago failing NOX at 15mph because of a bad PCV, you might wanna try that also.

Btw, the integra we worked on also had a new aftermarket cat. welded on by the owner right before he came in.

 

yeah i drove around for a while before i had it smogged.
is a pcv valve expensive?


Modified by mark72 at 4:25 PM 2/24/2004

 

I'm not too familiar with that brand cat. but if it's a high flow.. that's probably your problem.

 

thanks for the help peoples.
i replaced my pcv valve and next to be relaced
is my o2 sensor.

 

it could be ur cat. I failed smog with a carsound cat which was practically new and used a brand new oem cat and passed. i would also check spark plug gap and plugs that came with the car. alsotry putting back ur stock intake and header. that helped me with my smog. if that doesnt do it try a new o2 sensor cause it could be going bad.

 

run 87 octane, and pour a bottle of rubbing alcohol into your tank

buy a bottle of sea foam, and follow the intsructions

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mark72 &raquo;</TD></TR><TR><TD CLASS="quote">yeah i drove around for a while before i had it smogged.
is a pcv valve expensive?


Modified by mark72 at 4:25 PM 2/24/2004</TD></TR></TABLE>

I wouldn't worry about the PCV, I have only ever seen 2 valves go bad in all my years of working as a Honda Tech. And both of those situations were due to HUGE amounts of blowby coupled with lack of regular oil changes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Huggy Bear &raquo;</TD></TR><TR><TD CLASS="quote">run 87 octane, and pour a bottle of rubbing alcohol into your tank

buy a bottle of sea foam, and follow the intsructions</TD></TR></TABLE>

wtf is sea foam and who carry's it?

 

Change your DC headers back to your stock LS headers. DC headers are Carb E.O. but try it out with your stock headers on. Check your timing also, I believe your stock ignition timing is supose to be 16 degrees. You might want to retard your timing a little to lower the NOX. You are allowed 16 degrees plus or minus 2 degrees. So you can be at 14 degrees and still be within specs to pass inspection and maybe even your smog check. And make sure your whole exhaust system is sealed up pretty good without any air leaks. You are not to far off, as I've seen numbers near 3000.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mark72 &raquo;</TD></TR><TR><TD CLASS="quote">

wtf is sea foam and who carry's it?</TD></TR></TABLE>

napa, and it removes carbon deposits in the cumbustion chambers intake and exhaust runners

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Huggy Bear &raquo;</TD></TR><TR><TD CLASS="quote">run 87 octane, and pour a bottle of rubbing alcohol into your tank

buy a bottle of sea foam, and follow the intsructions</TD></TR></TABLE>

i would read this before using seafoam https://honda-tech.com/zerothread?id=780762

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SoCalAutotech &raquo;</TD></TR><TR><TD CLASS="quote">You said it a carsound cat? If you are driving a 95 Integra that should be OBDII. Car sound does not make a OBDII cert cat converter. I know its not CARB leagal. Chances are its not a 3 way cat.
</TD></TR></TABLE>

your off to the left buddy...
96+ obd2
carsound does make obd2 cats

 

does timing play a huge factor towards
high nox?

 

95's are OBD1

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hair_rice &raquo;</TD></TR><TR><TD CLASS="quote">95's are OBD1</TD></TR></TABLE>
i know that. i just want to know if
timing is an important issue when smogging a car?