I failed emissions a couple weeks ago, because of NOx. Standard was 2.2 actual was 2.37. I replaced the egr and cat less than a week ago, and failed once again today. Results:

Allowed/Actual

HC (GPM)
1.0/.66

CO (GPM)
20.0/.01

NOx (GPM)
2.2/2.76

CO2 (GPM)
NA/398.03

Does the cat need more time to be broken in, and what else can be done for this? I can scan the graphs if needed.

 

You need to cool down the combustion shambers more. Add more EGR (not easy), add alcohol to the miixture, clean the chambers before testing again to remove carbon, make sure timing is advanced correctly.

A cat converter generally doesn't need a break in, but it needs to be hot to work properly. Some of the old design cats also need an air supply to complete the NOx conversion. If you have an OEM cat and not a 3-way replacement, you need to be sure the A.I.R. system is connected and working correctly.

 

How long since you changed the O2 sensor?

 

Im not sure about the O2 sensor, it doesnt look to new, how much do they go for at a place like advance or autozone?

 

Usually varies between $20-$30.