Major problems after Cat failure
 

I have some major problems with my 2007 6 speed. It all started yesterday morning. Prior to the problems, the car was running great, with no issues, strange noises, nothing. I left for work, and got onto the freeway. Suddenly, I had a total loss of power, and had to work to keep the engine running. I turned back home, and about a block away, massive amounts of smoke came up from the engine bay. The Cat was clogged, and got so hot that the O2 connector caught fire.

The car is out of warranty (6 months) so I take it to the dealer. The changed the cat and O2 under warranty, but recommended changing the plugs, coils and wires for....wait for it...$960.00. I passed on that, and picked the car up this morning. I tried to drive to work, and the car was way underpowered, and then on the off ramp it died again. I had it towed to my mechanic (as my experience with the dealer was not good at all.

What my mechanic found today was a bit troubling, and I wanted some input as to what this may mean.

We pulled all four plugs. The front rotor plugs have a black oil type deposits on them, and the rear rotor plugs look more light brown chalky (in piston cars, I would say the front rotor is running richer, and the back running lean) Also, one of the rear spark plug posts was totally sheared off, and was oxidized (been broken for a while I am guessing. Another plug had rust on it.

As I said, the car had 34k miles and I was about to change plugs and wires.

We put new plugs (old wires and coils) and the car runs, but not well at all.

What is going on with the plugs, and what could change the car from running fine before the cat plugging, and making it run so bad now?

Any help would be appreciated.

I would change the ignition coils too, as sometimes the cat problem comes from the coils, if one or more is faulty...

change plugs yourself. get them online for 80 bucks. clogged cats are common your not redlining enouph

I redline almost every day. What really bothers me is the difference in plug deposits between the rotors. Also, how can a cat going bad effect a coil basically overnight?

^ it's the other way around, coil going bad effects the cat....

bad coils on the front account for the deposits on those plugs. the light brown is how they should look if firing properly.