Ok once again an age old question will be posted again I failed smog I have a 84 gsl all stock except for the magnaflow cat I just installed after failing
My numbers are as follows:
15mph HC 414 max 104 CO .83 max .89 NO 199 max 834 CO2 was 13.9% and O2 was .2%
25mph HC 170 max 86 CO 1.13 max .69 NO 94 max 715 CO2 13.7% O2 0.0%
Will I pass with a new cat or is it more I changed plugs and will get an oil change before hand and like I said I just put a new magnaflow cat in

 

The 0.2% and 0.0% O2 values suggest that there may be little or no additional air being pumped into the exhaust. The car has an air pump, right? Typically, you will see excess 02 after the bulk of the CO and HC are converted. In your case, it shows basically none, which could mean there isn't enough to begin with.

I would check that the secondary air injection system is working properly. Air pumps can lose their seals, solenoids can have broken wires, etc... There will be testing info in the manual. Links in the 1st gen FAQ.

 

Yes it has the air pump I will check and make sure it is working. Thank you. Also upon replacing my cat I noticed inside was lose and broken inside some. So I was thinking after I pass smog would it be worth it to put the old one in after I punch it out?

 

If the old cat had pieces broken inside, it was junk. You should see improvement just from replacing it. If you want to punch out the rest of it and use it as a straight pipe later, it'll be fine. You'll pick up a bit of power, but it will be a little louder.