Catalytic Converter Life Expectancy

[fxpthl]

My 97 Miata has 166K mile on the clock and seems to be running pretty good. I have a dumb question regarding the life expectancy of the catalytic converter and if it is replaced, what,if anything, will I see in performance gain/loss? The engine has a "spark knock" sound during hard acceleration and I am wondering if this is a sign that the converter has gone dead. Someone told me that the timing may be off and that could cause the knocking. I have also been told to use a higher grade of gasoline to resolve this issue. What say ye all on this subject? I'm listening!!!

 

[THE Phen]

I had a cat fail in an 84 Mercedes I was driving for a bit. It actually got plugged up. The cat would glow cherry red, and the car would just run like absolute crap. It would sputter, hesitate, barely stay running. Of course, YMMV, but those are what has happened to me.

 

[AutotownMazda]

A couple of thoughts for you. The car didn't detonate (aka ping, aka spark knock) when it was new so something should be repaired to eliminate the detonation. Putting in higher octane might work, but that's just an expensive band-aid that will fail to mask the problem eventually.

My 1990 BMW I used to own had 160k with the original cat and it was running clean as a whistle. If maintained properly cat's can last a long time. The legal warranty on a cat is 80K miles which gives me the feeling that they should last a long time. With that said, a cat that isn't working properly will raise emissions but won't affect the cars drivability (unless it's plugged/restricted) because the oxygen sensor before the cat is the one used to help determine fuel metering. On that note oxygen sensors have a recommended replacement of 100k miles. So if you haven't done that you might want to.

There are a lot of factors that can contribute to detonation, but it's unlikely to be the cat.

Autotown Mazda
Chris

 

[fxpthl]

Thanks AutoTownMazda, that really was a good description of cats. and what they are expected to do lifetime wise. I will look in other areas for this detonation issue. How about the timing?