This involves a 2003 Vibe AWD with 150k miles.
I was told by a mechanic a back pressure test was off the charts, making the catalytic converter a likely culprit. Since I had to drive 350 miles to get the car, I drilled a couple holes ahead of the cat near the second 02 sensor--per the mechanic's recommendation--to let off the pressure.. I got home and cut off the old cat thinking I could install a universal cat, given the $400+ cost of an OEM. After not being able to adequately fit a universal (and now I can't return it), I took off the piece just below the exhaust manifold, and to my surprise I find another "honeycomb" looking things which is called an Exhaust Manifold Catalytic Converter. (http://parts.nalleygmc.com/products/Pon ... 71578.html" onclick="window.open(this.href);return false;) Gee, I wonder if that's the one that's plugged. The cost of that one alone? Another $400+ dollars.
I'm going to make a home made back pressure gauge to see if there is any back pressure now that almost everything is off the exhaust.
Any suggestions? Do we really need to have two catalytic converters in a car?