So I took off my 02 sensor and looked insde the whole and saw a bunch of honeycomb. Is that normal? Im getting weird idle so I was thinking it was the o2 sensor. But I replaced it but still get the same issue. Anyone has a pic of the inside of the whole where the 02 sensor goes should look like?? This is the downstream on the cat.

 

You looked inside the O2 sensor hole in the cat pipe and saw chunks of honeycomb? No, that is not normal. If you saw chunks of honeycomb you need to replace the cat ASAP.

 

If you are looking perpendicular to the exhaust flow through the O2 sensor hole and can see honeycomb, where you can see the individual cells, then no, that is not normal. You should only be able to see the honeycomb cells when looking along the path of the exhaust, from the header end of the cat, at the flange: (this one is partially clogged i believe, but gives the right impression of the front honeycomb)





If you are seeing chunks like this through the O2 hole, it's definitely bad (this one has a crumbled front honeycomb, laying against the rear one, the tip of the rear O2 sensor is visible)

 

I only looked at where the 02 sensor was. I saw that the honeycomb was showing allot. But its been a while since I last saw that. So if anyone has pics of how it should look then I know its not the cat or it is. What cells should I be getting if the cat is bad?

 

You shouldn't see any honeycomb at all if you were only looking in through the O2 sensor hole. The honeycomb in it's proper position would be out of sight in each direction.

 

yep I saw whitish color honeycomb. I can touch it if I wanted to. So if I look inside I shouldnt be able to see it at all? Should be a black hole?

 

You still haven't really answered if it's broken up chunks that you are seeing, or if it's like seeing to the side slightly and seeing a smooth wall of honeycomb.

 

thats the thing I want to see a pic of how it should look so I know if its broken or its stock....

I saw some and like a whole of honeycomb where the sensor was.....

 

See the pic I posted earlier. It's from a different angle, but that's what I mean by "chunked". It should be one continuous piece, for each element.

Here is an element just before it starts to chunk up (non-RX-8 cat)



So, what do you see?

 

hmm I think so then but it was a small hole so I did see it closed to the hole. and I saw a line that divided the honeycomb. It was white looking too.

would this give me what engine code?

 

In theory, P0420 is supposed to get thrown. However, our ECU only has a vague notion of how to throw that code, so you can remove the cat completely and still might not get it. A cat with even a piece of honeycomb left is probably never going to throw it. One of the flaws of trying to get dealers to recognize dead cats. They trust a computer to tell them, when the computer can't figure out that it's dead anyway. A misfire code from the failed cat is far more like to occur before any cat failure code, unfortunately.

 

ok im getting p0300 and I think p0301 Ill try to pick up a midpipe if I cant find a cat locally.