Bad cat in a 97 Olds w/only 55k miles. Causes?

Messages
22,695
Location
Dallas,Tx USA
My gf`s dad is thinking about buying a 97 Olds 88 that has only 55k original miles. The car is from the Baytown,Texas area. He did a Carfax on it and nothing came back weird. It has a bad cat. What would cause a cat to go bad on a car with on 55k miles? Is this a red flag and should he walk away from this one?
 
Messages
21,668
Location
Apple Valley, California
There is a reason that the converter died so soon. Might be simple like a bad 02 sensor or a problem such as oil or coolant getting into the cat. Is the milage documented? Could the miles have been rolled back somehow?
 
Messages
2,759
Location
CarMax
Cats don't commit suicide. They're murdered. Gotta find out what killed the cat. Chris is on track with the bad sensor idea, among other things.
 
Messages
18,264
Location
Michigan
[censored]/old gas maybe? Sounds like it was not used much. Bet you it did a bunch of very short trips. I would say replace the cat-any sensor that needs to be replaced after that-and enjoy.....
 
Messages
36,007
Location
ME
If you get this beware aftermarket cats have way less "stuff" in 'em and you may have to replace every other year right before inspection time. Or source out a good used cat. I would bring a code reader with you to check it out, and make sure all the I/M monitors are done and ready except for the obvious cat one and other dependent ones. (Get a flow chart) A shady seller could clear codes before offering for sale.
 

JTK

Messages
13,164
Location
Buffalo, NY
Yep, excess fuel loading from a misfire is the most common, coolant getting into the combustion chamber, or silicone (spray) poisoning. Maybe long term use with a bad O2 sensor could cause it, but I've never seen an O2 sensor make that drastic of a fuel trim change. Joel
 
Messages
14,733
Location
Santa Barbara, CA
 Originally Posted By: Eddie
Is not Texas one of the states where certain stations were geting leaded fuel by accident?
i wish i had that problem. my Volvo hates 91. the one time i filled it with VP 100 it ran so much better.
 
Messages
8,989
Location
Marshfield , MA
excess fuel is the usual cat killer. Replacing the cat wont help much if you dont fix the root cause. A buddy of mine claims to have rejuvenated a cat by running the engine for a short period of time with the vacuum to the fuel pressure regulator off. This induced a rich mixture. Then he fixed the leak and drove the car for an hour or two at speed to get the cat hot enough to cook off the gas n the cat. The trick, I'm guessing is to get the cat hot enough to burn off the carbon , but not to melt the porceline core.
 
Messages
36,007
Location
ME
I've heard of ECM programming that deliberately loads the cat with a measured amount of fuel. 1) a misfire on warming up, to warm it up faster 2) AFR of 9:1 at WOT, more than is needed for power enrichment/knock retard May be something to it.
 
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