Just took my 91' TT 300zx for an emissions test and it failed for NOx. Both at low speed and high.
Here are the results:
High Speed
Standard Result
HC 114 81
CO .63 .02
NOx 796 1569
Dil. >6 11.6

Low Speed
HC 117 85
CO .65 .02
NOx 879 1440
Dil. >6 11.9

What could the cause be? I don't have the cash to take it to a mechanic. Please help

 

I mean did you just clean it (assuming its a K&N type)? Is your Check engine light on? were you using high % ethanol gas?

Numbers look pretty close, could just need new plugs. What does she idle at?

 

What mods do you have?

 

I have a K&N air filter which I did not clean so I will try that. The engine light is not on and she idles around 900. I put in 93 octane all the time but never noticed etanol%. The car is not taking off it seems to choke and even if i hit the pedal it doesn't really want to move. The last mechanic who had it changed an injector and that didn't really fix the problem. I just need to pass inspection now so I can get it registered. I also just bought the car so I don't really know what was done to it prior.

 

OK... Air Filter... Fuel Filter... New Plugs... Try running it again. If you don't want to pay for a mechanic, you're going to have to TRY to be one yourself. Keep us updated.