sprtbiker

I have a 94 Civic and it failed the emmision of NOx but only in the 15 mph speed. At the faster speed of 25 mph it passed.

I had this problem a few years ago and used RXP from Autozone and it worked. Last year I did not have a problem. This year it failed again and the RXP did not work. What do you think it could be?

Thanks.

R666_EK

Cat is probably on its way out. Did you get the car real hot before you took it in. The cat is most efficient hot.

sprtbiker

That car was hot and it was a warm day too. After I put in the RXP stuff, I drove around for a good hour before I took it in and it still failed. Would it still be the cat? How much do they run?

sprtbiker

Just wanted to follow up.

I changed out the cat and my car did pass NOx but it barely passed. Guess I will find out next year when I do the inspection again if that solved my problem.

randomtask77

Is your car running rich?

EG6KILIN

dam were I live they don't do that any more I think is from 99 an up...unless you live in Wisconsin you don't have to worry about it....LOL

ddd4114

High NOx readings are typically the result of high combustion temperatures.

Are you using a stock ECU? What is your ignition timing? Is the engine stock? If not, what's been done to it? What spark plugs are you using, and how do they look?