Help passing emissions

[locknload68]

I've had my emissions checked twice and failed both times. The problem is the NOx.

The limit is 1313 ppm and the first time I was at 1688.4 ppm. So I looked on here for things to check to fix this. I made sure the EGR valve is working and made sure the timing is right. I also made sure all the spark plugs are looking good. Also made sure the PCV valve is good. A lot of people I ask about this say it's my catalytic convertor, however, it is only a year or so old.

I went and had it checked again today and after I checked that stuff, the NOx went up. Now it is reading 1840 ppm. This is really pissing me off. What else can I check?

[Civvy]

easy! take the air filter out for the emissions test. fix the problem later!