Cats don't report codes. That code comes from the ECU reading an out of spec between the pre and aft O2 sensors. What's the condition of those? They are easy to test with a multimeter, but if they've never been changed out, that's your most likely culprit just due to your mileage...or ..... if you used non OEM new ones when you did the manifolds. Test them and go from there. That may also clear your knock sensor and you're good to go. Solve one problem at a time...assess....repeat if necessary.
Do not put Seafoam into anything!! Seafoam is oil with a bit of rubbing alcohol like the doctor uses to clean where you are going to get a shot....it is not a chemical brew. The O2 sensors won't like that at all. It has the same effect downstream as bad rings...including the smoke cloud. Get a new mechanic if he's telling you to use that stuff. Consider that not a single auto manufacturer recommends Seafoam, Miracle Oil, etc. for anything. Only Seafoam recommends Seafoam.
Do not put Seafoam into anything!! Seafoam is oil with a bit of rubbing alcohol like the doctor uses to clean where you are going to get a shot....it is not a chemical brew. The O2 sensors won't like that at all. It has the same effect downstream as bad rings...including the smoke cloud. Get a new mechanic if he's telling you to use that stuff. Consider that not a single auto manufacturer recommends Seafoam, Miracle Oil, etc. for anything. Only Seafoam recommends Seafoam.
