dealer issue...new engine...no change...
 

i need advice -

car suddenly lost power while driving at a decent pace, pulled over...started driving again....now car hesitates/misfires at 4 and 6k rpm. no cel, only flashing for a few seconds then gone...after multiple visits to dealer they say mazda states engine replacement....after 5 weeks...car returned to me...i see new core...car feels peppy...but then STILL misfires at same rpms. turned around and parked at dealer...smoke that stank coming from under center of car....after another 2 weeks dealer says cel states intake valve of some sort is faulty...they replaced...no change. they are seemingly out of ideas and now have had my car for about one and a half months...thanks for the new engine i guess....

i am convinced it's cat but dealer won't pull it w/o check engine light...wth...

They reuse coils, ugs, and wires from the old engine. I bet one or more of those 12 parts has failed, they didnt catch it, and so you still have misfires, and in the normal course of RX-8 sequential failure, your cat is gone too now.

Dont pay the dealer for ignition parts, $280 or so to forum vendors and an hour of work with basic tools to replace them.

I pulled my cat off myself and showed them the damage when my cat failed. No CEL.

Dont let it go, next failure items will be O2 sensors and then the engine, or a car fire. Which happens first is luck of the draw.

Thanks for the advice. They did change the coils and plugs. I don't think the wires - I'm concerned its the cat bc of the smoking issue but they won't pull it without a cel. I have read on here that a clogged cat can cause power loss - but I am experiencing normal power with severe loss/misfire at only certain rpm ranges. Does this follow suit? I'm about to take my car back and take it to a small shop and have them pull the cat. I'm so frustrated and want to actually drive my baby while its warm out still.