Here is the deal, couple of weeks ago, my 8 started a sound just like a exhaust leak, looked and looked couldn't find it, couple days later drive down the road, big back fire noise, power basically just shuts off! So start it up, limp it home, would hardly run. Check Engine light is flashing at me. So get online, read that people have problems with the cats, so buy a Magna Flow cat, and replace the 02 sensor in the cat. Starts up just fine, then about a 1 minute later....it cuts power barely will stay running, and I smell a bad smell, thought, well just the new cat, and look under the car and it is glowing red. So killed it and ran here for help. Any ideas? I mean it starts up just fine and normal for about a minute and then goes into protect mode!

 

first off, get the code

second off, check your ignition system, sounds like you are dumping raw fuel into the cat

 

When was the last time the car was in for maintenance? What was done?

 

got the code po302 , misfire in cylinder 2 , and it list the possible causes, my guess is coils since they have never been changed since I bought it. But when I left Autozone, it cleared up for about 20 seconds, and ran normal , just dont know

 

start with coils, plugs, and wires. an operational 04 with original coils is unheard of.

 

So how many miles have you owned the car? That's the real number needed......however, it doesn't really matter now as other have said............. Y

ou're dumping fuel into the CAT due to either bad coils, plugs, or both and possibly wires(but less likely). If you continue you'll burn up the new CAT. This assumes that kitty has any hair left on it now.