I replaced my O2 sensors about 3,000 miles ago after i installed my headers with some Delphi sensors. Recently i ran some seafoam through it and im wondering if that fouled my O2 sensors. I put it into the fuel system, the crankcase and through the brake booster line. Would fouled O2 sensors cause knock retard because im getting some on my scanmaster. I also seem to be getting worse gas milage than before, but that might be because of short city trips and they way i drive it.

 

When the o2s went bad on my v6 it threw a code, and when I got on it it would spew black smoke (gas), also I lost about 5mpg.

Hope this helps.

 

My Formula ran like complete ***, and it ended up being a bad 0 2 sensor, and yes, I believe when scanned it to was picking up some knock at the time.