thomthoms3

iTrader: (1)

Also no CEL. I've kept a keen eye on it the whole way. The only time I got a CEL was with bad O2 sensors, which was fixed, and misfires from old ignition which was fixed with the BHR kit back in the fall.

thomthoms3

iTrader: (1)

You mean Kevin at RR will tell when he rebuilds it? Or are you talking about a muffler shop?

BigCajun

iTrader: (1)

I thought the PO420 below threshold code meant the cat was bad?

EuroTech

I would agree but this can be a "ghost" code for a bad rear 02 sensor as well so you have to test it first to rule out a faulty converter.

http://www.easterncatalytic.com/educ...he-po42o-code/

BigCajun

iTrader: (1)

Good article.
I had the code, my cat was bad, so I thought that's what it meant without giving it much thought.
I guess 2+2 is not always 4.

EuroTech

Being the engine electronics work together, the code stored doesn't generally mean the definition for said code means to replace the part it is pointing you towards. There can be other issues which will trigger a code ( i.e. pinout/loose connection, short to ground,etc) that will make it look as if the part in question might be bad when its not.

RIWWP

iTrader: (2)

The only way a cat failure on an RX-8 will throw P0420 is if the cat blows out, partially or completely, so that the rear O2 sees unfiltered exhaust. A CLOG is a restriction on exhaust flow, but the rear O2 sensor STILL sees properly filtered exhaust gasses (whatever small flow is getting through). So the ECU doesn't know anything is wrong.

The only real way for an ECU to tell if the cat is clogged is if it had a way of measuring the pressure difference between the front O2 sensor and after the 2nd cat element. Not something our ECU is monitoring, and we don't have sensors that can pick up that.

There might be a way through calculated EGTs between the two sensors, however it would require a lot of testing of good vs failed cats to determine what conditions a clog will show but no other situation does.



And yes, it is scary. It's one of the big reasons I am a proponent of going catless for the RX-8. Engine failures, sensor failures, and car fires have all happened from RX-8 cat clogs. And no, I'm not exagerating. There have been a handful of fires that burned the car to the ground. One example: https://www.rx8club.com/series-i-tro...e-help-244839/

thomthoms3

iTrader: (1)

I wish I could go catless. I would not be able to bear the sound of my car any louder than it is now with my catback.

RIWWP

iTrader: (2)

If sound is the only problem, the BHR midpipe is your solution. It mutes the catless volume down to almost the same level as the stock cat. Faintly louder, slightly deeper. No other midpipe can do it the way the BHR midpipe can.

BigCajun

iTrader: (1)

^^+1
My BHR with stock muffler is only slightly louder than with the cat, & gives it a deeper tone. It sounds really sweet at WOT, not loud at all.
If you keep your 8, I highly recommend it.
I'm sure someone would gladly trade your catback exhaust if it's aftermarket for a stock one if noise is a concern.