92 cierra with a 3.3,(3300?) ok i passed the smog test after changing plugs, oil, wires; i am getting better gas mileage, about 20 mpg up from about 10mpg. the smog test indicated high NO numbers. I checked the codes and the codes are clear. any idea as to what gas mileage should be on a 3.3 and what could be the cause of the high NO? thanks talipp...

Oxides of nitrogen, oxygen(s) combining with nitrogen in a molecular sort of way caused by high cylinder pressure in the presence of high combustion temperatures. The egr valve takes care of this during normal driving by allowing inert, nonreactive exhaust gasses into the intake air. This reduces the high combustion temperatures and the formation of oxides of nitrogen. It also lets the ignition timing stay advanced for better fuel milage...it all kinda works together in a beneficial sorta way.

ok where is the egr if my 3300 has one? it does not appear on the intake manifold like the manual says? thanks edsel...

ok just read that the 3300 does not have an egr? what else will cause the high NOx in the smog test?
I also have a slight miss at idle. any ideas as to how to correct thanks edsel...

It's like I wrote, oxygen(s) combining with nitrogen in a molecular sort of way caused by high cylinder pressure in the presence of high combustion temperatures. Driving at part throttle activates the EGR if you've got one. Without an EGR valve, maybe the catalytic converter is taking care of it. It was about that time that a "dual media" type converter was developed. Regardless, the car most likely has to be moving under power for much of this equipment to work. If the breakdown of NOX involves heat as a byproduct, you wouldn't want that to occur while sitting still as the converter could get hot enough to set something afire whereas driving would have airflow under the car to remove heat. I see those results on my smog tests also and can only guess as why the readings at idle are not sending up flags but the diesel engine mfg's are being required to address it.

I would definitely check coil packs, especially if they have never been replace. Also might want to check O2 sensor(s)

I would definitely check coil packs, especially if they have never been replace. Also might want to check O2 sensor(s)
how do i check the coil pack to see if they are good or bad?

Here's a link on how to test your coil packs:

http://members.fortunecity.com/slade901/automobile/Ignition_Troubleshooting.htm

You sound as though you have the same problem that I did. I did a full tune up just before my emissions test. Even though I have a different engine than you, must test results were like yours, high NOX, which is usually caused by a malfunctioning EGR valve - I had no codes either.

I even tried guaranteed to pass - and I still failed with high NOX. Finally I bit the bullet and went to a dyno/performance shop, and they gave the car the once over, and told me what I already knew, my car is running like a top. But I didn't know I needed a converter. went right to a muffler shop, got a converter and passed with flying colors.

what the EGR doesn't do, the Converter finishes. It actually converts the oxides of Nitrogen to Carbon Monoxide, of which one of the by-products is heat.