roastduck88

I just took a smog test in CA and I failed it because of high NoX, any ideas how i can solve it? I have a stock CAT, after market exhaust, spark plugs were changed recently.

upstatemax

iTrader: (15)

Make sure your EGR is working properly.

roastduck88

Thanks!

Yup EGR is working fine.

upstatemax

iTrader: (15)

Besides a CEL it might not open or close all the way thanks to the crud that builds up on the valve. If the EGR is not fully open you can fail a Nox test easy, especially in the recent heat.

carsarecool

iTrader: (1)

They actually do the sniffer test in CA?!

frankd121

iTrader: (1)

I believe you can determine abnormally high amounts of NOx through the OBD system.

NOx is created because of high (or excessive) combustion temperatures. You should scan for any codes; this might help you determine your exact problem.

roastduck88

Just scanned for codes, no codes either. Yeah.. CA takes readings at 15mph and thne at 25 mph.. those bassards!

5thgenmaxima

iTrader: (1)

+1 for what keeps being said. IIRC around 2500 + degrees fahrenheight.

Almost always EGR related, unless you have other engine issue. (misfire, lean condition, preignition, etc.)

First thing I would do is double check and make sure your egr system is working.

roastduck88

Thanks! I'll give it a shot.