Rx8 Idle Issue
 

I have a P0300 code (random multiple misfire code). The car turns on but won’t hold idle, it’ll stay on if i give it gas but will die down without throttle. I just replaced wires and coils, spark plugs were replaced not long ago as well they all look good. Any idea what this might be? I did replace the battery as well and reset NVRAM.
Also wanted to note, I have the cat disconnected at the front side because it is a bit clogged but i didn’t think that would make it die that easy. I’m trying to get it down to my buddies shop to get a midpipe built for it in place of the cat, and trying to avoid towing. Any tips?

Did you check your vacuum lines?

Also be sure your plug wires are separated with looms and not bundled together or pinched somewhere arcing out.

I assume you installed the coils and plugs in the right order?

This color coded chart is popular, but I made an idiot proof drawing, because crossing coils and plugs can be very, very bad.

https://cimg6.ibsrv.net/gimg/www.maz...8d2b143986.jpg
https://cimg6.ibsrv.net/gimg/www.maz...e33144daf5.jpg

You could always break out the cat strata with a crowbar if you're SURE it's bad.

A dependable cat for a Wankel will run you well over $1000 if you need it for emissions testing.

If you do this, then you need to be sure no broken pieces clog your catback exhaust.

Best way to be sure is to drop it and inspect it.