Technical question: why exactly do weak coils kill cats so fast?
 

So I recently changed my ignition from a dead OEM system to BHR and the next item on my repair list is a new cat. I've already decided on the BHR midpipe with cat because Washington requires emissions every 2 years and I can't pass with P0420 lit up. And there is no way in hell I'm paying $2k+ for an OEM cat. That's just ridiculous.

So just to understand the RX-8 better, I was hoping a techie could explain to me why weak or dead ignition coils kill cats so fast?

With weak coils fuel doesn't burn. Unburnt fuel reacts with the cat and burns. Too much fuel in the cat will cause it to over heat and melt.

Great, thanks. That would explain why it smelled so rich when I bought it and why it smells so much better after changing the coils.!

Note that ANY cause for excess unburnt fuel does the same thing. running rich, coils, plugs, wires, grounding points, maf, ess, vacuum leak, o2 sensor. even overfilling the oil can.

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I know for a fact the cat is dead, and I'll be ordering a BHR midpipe with cat in the coming week. Compression testing is on my list to do, but first I need to find a place around Seattle that even offers it. The Mazda dealers have yet to even call me back and a Google search returned nothing.

Any licensed Mazda dealer should be equipped to do a rotary compression test. If you get nowhere with Seattle area Mazda dealers, contact MNAO Contact Mazda - Mazda USA -

Awesome, thanks.

UMazda on Roosevelt and 45th just east of I-5

Thanks but I prefer to stay out of Seattle if I can. Crappy roads do not play well with nice cars.

Will the CAT installed inside the BHR pass emissions? If so, Charles maybe you can answer this - is there a way to buy that part separately?

I didn't do it at the beginning, but had to throw the OEM cat back on for emissions (still running into other problems x_x) but now just have the midpipe sitting out of my car.

So, I am debating if I should have a shop install the BHR cat onto the midpipe or sell it sadly.

I already contacted Charles, he said his catalyst will clear P0420 codes.

I'm not sure if his catalyst will fit other midpipes, however. That's a question for him to answer. Remember you can always email him at charles@blackhaloracing.com.