Hi group:

I'm a resident of new jersey and I just failed emissions, passed everything else.

Curiously, the car passed co and hc with flying colors, but failed nox. I was told it is not by alot, although the threshold was 970, and I scored about 1780.

I read the FAQs and came up with some help ful stuff, like cleaning the knock sensor. I noticed recently that the car's perf was sluggish.

Cleaning the sensor, which was a little wet, did help. It seems that if the sensor isn't working correctly, it retards the timing, which explains sluggish perf. and higher nox emissions.

The fuel pressure regulator is perhaps another culprit, but I can';t tell if it is bad, otherwise engine works fine. One thing I did notice was that the skinny tube that comes out and goes in to another part doesn't seem to have a super tight fit and so was a little worried that it was not sealed properly.

Any tips would be appreciated.

Thanks.

Advanced timing may increase the NOx emission as it causes the engine to run hotter. That is also why "ping" is a problem with advanced timing. The knock sensor is designed to detect the Pinging and retard the timing when it occurs, thus protecting the engine.

Check for air leaks in the intake system, another common source of high NOx. Any air that enters the intake after the amm is called 'false air'. This extra air causes the engine to run lean which increases the temperature and probability that some of the O2 will burn resulting in higher NOx production. That skinny tube and other vacuum hoses are prime candidates for creating false air. The faq is full of tips for air intake leaks and methods to find them.

Have you checked the base idle and CO adjustment per the faq?

If your car is equiped with an EGR system make sure it is operating correctly.

By the way, it may be your catalytic converter, but take a look at the easy stuff first.

Good Luck,

Dan

Thanks Dan:

I'm not sure if its the cat. It passed the other stuff, co and hc.

I'll check to find another hose for the fpr, it does seem like it may not be a tight fit.

Base idle in gear is too low, around 500 rpm. Neutral idle is I think about right at around 750 rpm.

I guess I need to keep checking.

Thanks.

David