I have a 90 cb7, when I smogged my car numerious times it failed the nox emisions. Across the board it was all low, the co, hydro carbons and o2 was all below average. But the nox was way above average it was like 1800 points on the 15 and 1500 on the 25mph test. So far I have replaced the cat, cleaned out the egr ports, checked vacume to egr, cleaned the intake, flushed and replaced cooliant, checked compression steady on all four around 180 to 200 psi and changed the ect sensor but still has not passed. i dont have the money for a diagnostic ryt now. The only thing that I can think of is my ignition is a msd blaster 2 coil, can that be the reason my nox is so high? and why all the other tests are below average? N E help will be most apprecihated.
I posted in the accord forum but there are few that have enough sense to give me a legitamet answer

 

so nobody here either? I was told bout cold plugs n e info on if those will help?

 

so your other post did not provide any other info ? if you don't want to believe anyone on here then just install the new plugs see what happens.
seem like your not liking the help your getting.
or spend some money and have it looked at .

 

dont know why your nox is so high, when mine was it was the cat but you said you already replaced that. BUT i might have some usefull info for you. I don't know the specifics but i know if youve owned your car for 2 years or longer the state will pay like up to $500 on smog related repairs. I'd look into this if i were you...

 

what is your AFR ?

 

has the ecu fuel and timing been changed from stock?

 

post some data list info like st/lt fuel trim and map and o2 readings,also hit count readings

 

There are a few things that can cause Nox to go up. EGR if it has one, Cat , Timing- Both cam and ignition and plugs. I would start there.