Rep Power: 0

I have a Honda Civic ex 1997 d16y8 ( single cam vtec) I failed smog due to high NOX in the 15 mph at 2010 rpm it was at 575 and the max amount is 487. I passed the 25 mph at 2148 rpm with 177 max 774. This led to think it was the egr but I don't believe my car has an egr. I recently bought the car replaced cracked Exhaust mani. I have an extra o2 sensor that I'll swap out and the oil needs to be changed as well as new spark plugs and possibly cap and rotor( that shouldn't effect NOX right?) the car idles at 600 rpm if not lower. Temp gauge never goes over half even when I'm driving hard or if it just sitting. Fan does come on. No CEL. 188k miles looks like a lot of carbon build up on Pistons. Someone please help...

 
Rep Power: 175

Yes, you do. It's above the right side of your valve cover. You could try removing and cleaning it.

Good or cheap brand? No more leaks?

Upstream (pre-cat) or downstream (post-cat)? What brand? Maybe do both if you have the money.

It could. How old is that oil? How does your catalytic converter look? A whole bunch of crap in it could reduce the efficiency of the converter.

You might want to use an additive like Seafoam if it's really bad. Especially if you're going to do an oil change soon anyway. Maybe also a quality fuel additive like Techron too.

HTH

 
Rep Power: 519

Does it have EGR?? I'm not seeing it from here.

*Running hot,
*poor fuel control by the PCM,
*elevated compression ratio due to that carbon buildup on the pistons,
* (if equipped) faulty EGR or clogged passages
*ignition timing problems
*A worn out cat can cause high NOX too.

Maybe more......
I don't have to deal with emissions testing where I live.

 
Rep Power: 0

Used OEM Exhaust Mani, Unknown Brands on O2 sensors. Just SeaFoamed Car Idling a lot better almost normal, added fuel additives will be doing oil change cat looks normal to me unsure what you mean? And Ill have to check for the EGR, I looked through OBD scanner it said N/A. Thank you guys really Appreciate the help.

 
Rep Power: 0

O2 Sensor Up stream/ On the manifold. *

 
Rep Power: 519

That's the manifold only, not the cat...correct? Just wondering here.

 
Rep Power: 0

Yes correct