Do it wrong, do it
twice. Do it right,
do it once.
Join Date: Mar 2011
Location: New Zealand
Unfortunately as the post cat sensor signals are approaching 1 volt I would say your cat may have seen better days. If you get two new cats make sure the person who is going to fit them knows what they are doing. If I could go back in time I would have taken my car to a performance exhaust place and had sports cats fitted. Sports cats don't break up like standard ceramic cats but are more expensive.
If you look at the oxygen sensor plot I posted you will see the purple line looks a lot like your post cat readings, and the purple line was the reading from my damaged cat.
After I got mine replaced, apart from the leaks it drove much better, most notably when changing gears or driving through a carpark. If you asked me was it worth it I would say yes but I regret not spending more to have it fixed without any hassles. To put it anoughter way, I could now sell the car for a bearable price.
(Mechanical Engineer + Mechanic - Alfa)*time = ln(Bad News)
Last edited by MGG; 04-04-12 at 05:55.