Hey I'm new to the forum and semi new nthe the rotary,
I have 2010 rx8 was running great untill, hit a bump high enough it damaged downstream o2 sensor, knocked some catalyst loose,
was getting cylinder 2 misfire codes, and basicaly everything that said converter was hooped,
replaced cat and downstream o2 sensor, as well as plugs and wires coils, and then i was getting code for MAF sensor so did that aswell..
then i was getting codes relating to highflow intake stuck open, so i checked and cleaned that made sure it was woiking fine and it is just fine.
still rough idle and has no power at all. burning fuel like crazy,,, popping underneath the car while driving, and blowing some smoke. smells like burning rich and the occasional back fire..
the popping under the car does not sound right.. Any ideas? thanks in advance!!!

 

Have you replaced the ignition coils? Possible there are pieces of cat blocking the exhaust downstream? Popping doesn't sound right at all the precat gasket on the 8 is not super reusable, it could be causing a leak. Get a new one from Mazda. Parts store gaskets don't live long at 1800F EGT.

Can you read OBD data? Check the fuel trims and airflow grams/sec on a fully warmed up idle and report back.

What cat did you put on there? Definitely do not drive it like this, you'll kill the cat and the engine.

 

As much damage as you did to the exhaust, it sounds like an exhaust leak related to something further upstream. It's all rigidly connected. Check the exhaust manifold to the cat for cracks and leaks and such. Not sure how that would cause all your intake related issues, but there's at least that glaring issue.