What are some symptoms of bad o2's? I am running a little ricj I believe bcause of the black "smoke" and build-up on my bumper. I heard it is probably bad 02's not to mention I wouldn't doubt if they are the original ones on there. Can't hurt to change them but is this a sign of bad 02's?

 

O2's can cause such a problem. But then so could a dozen other things. I fear that if you are running that rich, your cat is probably gone now. It can never hurt to replace the O2's with only OEM pieces. But this can be a bit expensive. And if it turns out they aren't the reason and it still runs rich, you could screw up the new ones. A high amount of back pressure could cause your problem also. As in plugged cat from running too rich. Something worth checking.

The first thing to look at is the air filter. The next thing you may want to do is tune it up if it hasn't been done in a while. Plugs, wires, fuel filter and you may want to think about a distributor. Most vehicles with a distributor can get just a cap and rotor. Unfortunately the opti distributor has a bearing that will go bad so it's best just to replace the whole unit. 93-94 opti's also have a carbon tracking problem.

Again assuming these things haven't been done in a long time. After that you could scan the O2's to see how they are reading and then decide if you need them. Another over looked item is the TPS and they wear just like any other mechanical device. Not expensive to replace.

Along with the tune up, it wouldn't be a bad idea to clean such items as the IAC, TB and the EGR. Check the EGR while it's off to see if it is binding and don't forget the gaskets.

 

I believe the cat is already gutted because there are hammer dings all over it and it has the sound of a gutted cat. All ignition parts are new so I guess that leaves the o2's, and everything you mentioned to check. I am thinking of getting new TB gaskets and taking it off and cleaning it anyway. Anyone know of a good aftermarket high flow cat?