Been trying to get my car to pass emissions test this week and not having much luck! I'm good in all areas except Nox ( Nitrogen Oxides) my 99 z34 with an L36 3800 is failing inthis area with a ppm around 560 where 421 is the limit. I've tested with 2 differnt egrs's aswell? Apparently my combustion chamber temps are running hot, I noticed this as soon as I bought the car when it took no time at all for the exhaust to start getting hot and spappin and craclin like I'd been on the highway for some time. Was wondering if anyone had any insight as to where to look next to fix this problem and lower my Nox. Thanks.[/align]

 

Maybe check out your catalytic converter or O2 sensor or both.

 

The car passed on it's last e-test so obviously something has changed from then to now.The car was only driven for about six months after that and then sat for a year after my buddy bought his new Monte. The only thing I can think of is something with the first O2 sensor or the Cat. I only have to drive the car about 5 minutes and the exhaust is already heated to the point that it starts cracklin and pingin like it's been goin down the highway for a long drive. Any help would be appreciated, I'm close getting this car put on the scope to see whats up.