Quote:
Originally Posted by notfarnow
can't wait to hear the experts chime in, I was wondering about this too
My understanding is that the cat doesn't affect *performance* because there is nothing measuring its operation & output. It cleans up the emissions, but doesn't give any feedback into the ECU to affect driveability or power.
The exception is if it's plugged and causing excessive backpressure, but that is a mechanical issue, not a sensor/computer one.
Mind you, this is my understanding based on 10+ yr old cars that I've owned. Probably the newer, more complex cars measure post-cat emissions
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I realize that they get plugged and can affect performance, my question was "how can you tell when it's getting plugged?" It might be easy to tell if one is completely plugged, but how about only partially? I'm thinking that they do not plug-up all at once, that it's a gradual process. A partially plugged car would simply rob you of power and efficiency, w/o any blatant symptoms.
The O2 sensor question is a separate issue. What will a bad sensor (or 2) do? Do they affect mixture all through the rpm range, such as under light acceleration?
New cats, or even used ones, are very expensive and not the kind of thing that I would change just for the *why not* of it. Same w/ sensors, I'd need minimum (2) @ ~$150 each. I need to know how to diagnose them.
FWIW, slodave, new cats are out of the question for me. I found a set of super-low mileage used ones at a Porsche salvage for about $300/set, as opposed to ~$1k
each brand new. It is not a part that wears quickly, they often last 200k miles or more. Good luck.
