Originally Posted by
tomw
If you don't poison the catalytic converter with anti-freeze or RTV silicone, it can last forever. They do not wear out, they get killed. I still have one on my car that has 245k. The SMOG test numbers are still good, and it gets decent fuel mileage.
The culprits you could look for are 1)fuel pressure regulator 2)Air and coolant temp sensors (ACT & ECT), 3)your thermostat 4)ignition components 5)air cleaner 6)engine timing 7)all that extra cr*p you carry around in the back of the truck and 8)tire pressure. Not necessarily in that order, but some are easy to eliminate..
tom
I second that, my Dad's 1996 Ranger 2.3L has over 300,000 miles and still has the original cat. According to him, it also got 29+ mph on the last tank. A lot of people like to jump tot he cat as inhibiting performance and causing bad gas mileage, when in reality it is usually the opposite, something goes terribly wrong with the vehicles fuel management, causing poor performance and bad gas mileage, and it takes the cat down with it.