I just bought a high mileage teg and when smogged it has high NoX levels. I have been told this is due to high combustion temps??? but what does that mean? too much grime on the valves?? I want to fix, but dont knwo what to do? Should I swap the engine for a rebuilt? Try getting a new exhaust? maybe cat is bad? Or can I just take off the head and have the valves cleaned?

Any way I want a new exhaust, what is the best way to do a whole header, cat and exhaust system for cali "enhanced areas" . I want the teg to look good run good and be legal. is this possible???

 

Back off the ignition timing.

I'd also look into the cooling system.

 

What year and model do you have?

 

its a 90 stock GS model with 210,000 miles. The engine sounds good.