> From: David Massey
>
> Dunno. Just that the new cars with computerized fuel
> management control
> the fuel/air ratio very very accurately and there are no
> problems with the
> cats.
Oh, I wouldn't say that. The entire mixture control thing depends on the
lambda or O2 sensor working correctly, and they definitely have a limited
lifetime. At the end of their lifetime, they start reading too lean. If
the computer doesn't detect that the O2 sensor is defective (and it's a
gradual process, somewhat hard to define precisely), then it can overcorrect
the mixture too rich, which can cause an overheated converter. Having
computerized cars come in with red hot converters is a common sight in most
repair shops. This is a particular problem in cars with analog computers,
since they aren't very 'smart'.
Also, many cars with converters carry warnings not to hold them at fast idle
too long, because of the potential for converter overheating. The converter
naturally generates heat (and has to be hot to work), the design relies on
air flow under the car to keep other things cool.
Randall
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