This is on obd1 DX, all stock but failed with NOx. The car fuel economy isn't so great, but paper suggest it might be running lean, air intake temps too high, bad oxygen sensor and few otheres. there are no cooling issues with the car. I was thinking to replace ignition components, like spark plugs or will that make things worse?

 

you must have a check engine light on?if so check it
replace whats bad like u said the o2, some fresh plugs and if all fail retard that bitch, in turn should lower the temps and create lower NOx to much NOx is caused by exhaust temps reaching over 2,500 degrees!

 

there are no cel's.. i'm gonna replace sparks, maybe rotor, check timing and pull it back to maybe 14. any other ideas?

 

see if this helps https://honda-tech.com/zerothread?id=313708

 

thanks, it has a post regarding NOx.