Howdy all -

I purchased genuine Mazda coils from eBay (uh oh, I will get flamed for buying anything from eBay), NGK wires and spark plugs and installed them in my '07 RX8 with 125,000 miles. I've done plugs and wires before, but never coils. I know, I know...a long time, but my car never exhibited problems until last month, when it shut down at a racetrack.

As preventative maintenance, I replaced the coils (and also plugs and wires) with these genuine mazda coils, and on the test drive around, the car threw a blinking check engine light, stumbled, and got really hot. By the time I found a place to safely pull over, the car began to smoke. The carpet inside melted.

I had the car towed to the local mazda dealership. The service advisor and I checked the wires (he wanted to see if I effed up the trailing and leading plug wire install, understandably), and to make sure I pressed the plugs wires down tightly. Visual checks aside, he told me that it's pretty clear the cat failed. And that he'd check the compression and coil packs early next week.

I guess I'm wondering - could it be that one of my new coilpacks was DOA, causing unspent fuel to reach the cat? If so, wouldn't the eBay seller at least be responsible for sending me new coils?

I know I need a new cat, I just don't want to pay for new coils, plugs and wires too. Or engine.

 

this statement alone removes any speculation that the coils you were provided were bad.

I wouldn't be surprised if you were running with bad coils and slowly killing your cat for a while now. With the new coils, your car was burning more efficiently, and probably put the finishing touch on an already damaged cat.

Sounds like your preventative maintenance came about 90,000 miles too late.

 

hopefully it's just the cat then. I've been wanting to put on a black halo racing resonator (with catalyst) on for a while.

Thanks!