Bob Tom <tigers@bserv.com> wrote:
[...]
: The code was set because the pcm detected the catalyst sensor"s
: switch rate (I have no idea what this is nor that we have one) was too
: close to that of the O2 sensor's switch rate.
I believe what that means is that the rate at which the post-cat
(downstream) O2 sensor was going between rich and lean is almost
the same as the pre-cat (upstream) O2 sensor. (I suspect that what
they are referring to as a "switch" is any time the air/fuel ratio
at the O2 sensor goes past 14.7:1 in either direction.)
The downstream O2 sensor should move between rich and lean much
more slowly than the upstream O2 sensor and not respond as quickly
to changes as the upstream O2 sensor. The reason being of course
because the exhaust gasses have to go through the cat before they
reach the downstream sensor, and in the process they are altered
considerably. If these two sensors start to act in the same way,
the computer assumes that the cat is no longer altering the exhaust
gasses sufficiently, and throws this code to indicate that the cat
is probably in need of replacement.
That's my edumacated guess on it anyway! :-)
--
-Jon-
.-- Jon Steiger ---- jon@dakota-truck.net or jon@jonsteiger.com --.
| 1970 Barracuda - 1990 Dakota 'vert - 1992 Ram 4x4 - 1996 Dakota |
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