i couldnt pass smog today, everything was ok except the NOX was like 1300 and the limit was 700, anyone have any ideas, any help would be great, thanks again stangers!!!
Production of NOx is exacerbated by high combustion temps. Anything that will reduce those usually helps - be sure egr is working as stated above (while it seems counterintuitive, that cools the chamber), the fuel additives designed for passing emissions test help, be sure the timing is set at 10 btdc, some go back another degree or 2 to 8. The same changes that help with NOx can hurt with unburned hydrocarbons (HC) - so be careful. That's the nature of trying to control these things - what helps in one area usually hurts in another.