I’ve had this car for 2 1/2 years now. When I bought it it wouldn’t pass smog and all I really had to do was get a new cat. I’ve always noticed that my car seemed to run rich from the smell of the exhaust but didn’t really care too much as I am still getting 27 mpg. Well, I just had my exhaust redone, (rusted through resonator - rusted out exhaust canister that sounds like a can full of gravel) and when he went to put the 2 yr old cat on the new exhaust he showed me that it was completely melted through, he told me that it was a symptom of a rich running engine. It’s completely stock with only a CAI. I replaced my O2 sensor when I replaced the cat, and I just put new NGK plugs and wires along with a new rotor in the dist. Any ideas why a stock motor would be running so rich.
i’d start by checking the timing. you should also check the resistance of the coolant temp sensor. first cold, then hot
you may not necessarily be running “rich”. rich is a condition of excess fuel to air ratio. it’s possible that you’re not burning fuel adequately.
and if you’re not burning fuel adequately, it doesn’t take long before the o2 sensor becomes contaminated and won’t function as it should.
aftermarket cats use much lower grade metals than oe. they tend to burn out very quickly, even in a system that’s operating correctly.
That was my thought. I just did a swap to a recently rebuilt OBD1 long block, and I was thinking that I never messed with the timing I just slapped the distributor on, in the middle of it’s adjustability, to get it running and never did anything with it afterward. Though I did not know that about the aftermarket cats being inferior, I’ll look into getting an OE replacement and new O2 sensor, and see if that helps.
what about a magnaflow oe replacement cat? its a reputable company, yet i burned through half my cat with a total run time of about 4 months. the piping did crack just before the catalyst about 3 weeks before i took it off if that makes a difference