Emissions Test: N.O. Too high? How to fix?

[thewoahna]

It is that time again, my car needs to pass the Ohio E-Check. I took it in today and the N.O. rating was too high and I failed the check. The only thing that I have changed on the car since the last test (2 years ago when I passed) was install a different header and O2 Sensor. Would this cause me to fail? Is there something I can add to my fuel or some "trick" I can do to make my N.O. levels lower?

[bruno8747]

High NOx is cause by blocked egr ports

[93twodoorLX]

try taking off your EGR valve and pouring a little Seafoam in there, let it sit for like 10 minutes then idle the car for a few and then go drive it for a few. like bruno said i believe it is caused by blocked EGR ports

-sean

[92cord]

Ken, how much higher was the NOx level? How long ago did you change your o2 sensor? If you need help, you got my number.

[wed3k]

the only real way to clean those out is via service plugs.

after i got mine cleaned out, and passed smog, i put on a block off plate so they dont get clogged again

govenator arnold paid for my repairs.

[NorcoAccord]

your cat may have also gone bad, when was it last replaced?

[f22-dohc]

effing hell.

my NOX was 3 times the limit.

imma wait on someone as they changed cat and he is brining it in cold temp

[radiuslight]

Yep....
If you failed Nox then you have restriction and residue build up in the EGR system.......
A clogged EGR valve does not make you fail but it helps......
Its more common to fail from clogged EGR port holes!

Clean the EGR like they mention above.....seafoam,carb or intake cleaner will do fine! Whatever you do........Do not block off the EGR valve it might not affect MPG's too much but it will make your car sound like shit!
Don't listen to anyone that tells you that!

[4CYLPOWER92]

Aside from cleaning EGR ports and valve, it will help alot to retard your ignition timming 1 or 2 degrees. This will lower the combustion temperatures and reduce NO greatly. You can also run the colder spark plugs.

[Leung]

woah Ohio re-instated the Echeck? or is it only where you live because i haven't heard that it was in Cincy.

[jhondayaaj]

Aside from cleaning EGR ports and valve, it will help alot to retard your ignition timming 1 or 2 degrees. This will lower the combustion temperatures and reduce NO greatly. You can also run the colder spark plugs.

x's 2.......

[AD5OS]

was your car at full temperature... the Cat works best when it is very hot... run the engine for at least 30-45 min before taking that in to get checked. Also I would recommend using some E85 in the tank... get a good 50/50 percentage of ethanol and gas in there. It will reduce your NOx and CO levels.

As far as cleaning out your EGR valve and ports.... it is easier if you dont have a 90 accord where you dont have to drill them out and plug them back in. I would recommend just taking off the whole intake and cleaning it all out with several bottles of carb cleaner and new gaskets. I've done the whole EGR valve off and pouring in seafoam and it created a HUGE mess. I wouldn't recommend using seafoam.. just carb cleaner! The sea foam takes way longer to dry out than carb cleaner and its easier to just spray in carb cleaner a lil bit at a time while the car is idling to clean out the ports. Also I used a LONG thin wire to scrape out the carbon. I've heard people just using a long wire and a vacuum... that might be a good start before you spray carb cleaner or seafoam.