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mike100 · 02-04-2015

additional ignition timing would elevate NOx, but usually the port throttle closed timing map at the lower rev ranges doesn't deviate from stock much on some tunes.

If the other numbers were looking good except for NOx you surely need new O2 sensors. Cleaned my car right up. I will need to see your exact results for a more specific diagnosis though. Another easy fix is if you have a bad vacuum leak under the plenum somewhere (you can tell by a high idle).

I got the oxygen sensors from O'Reillys- they have the proper length 3 conductor wire harnesses.

02-04-2015	#6
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: Just Failed CA Smog. Now what? additional ignition timing would elevate NOx, but usually the port throttle closed timing map at the lower rev ranges doesn't deviate from stock much on some tunes. If the other numbers were looking good except for NOx you surely need new O2 sensors. Cleaned my car right up. I will need to see your exact results for a more specific diagnosis though. Another easy fix is if you have a bad vacuum leak under the plenum somewhere (you can tell by a high idle). I got the oxygen sensors from O'Reillys- they have the proper length 3 conductor wire harnesses.