[Shotimes] Sensors (finished)...was: Leather Seats, Woodgrain kits, and Oxygen Sensors!

[George Fourchy]

Duh.....meant to store this to finish it, but sent it by mistake........

On Sat, 28 Dec 2002 01:04:15 -0500, Chris \"Zap\" wrote:

>Yet another pondering about random SHO ideas lately....
>
>First of all, I wanted to confirm that replacing an oxygen sensor that isn't
>throwing any code has no benefit.  I figured that it isn't worth spending
>$40 if it will work the same as the current one.  I know there is a testing
>procedure on SHOTimes, which I plan to use on the bad one (I think its the
>wiring, because it is intermittant), but I remember a debate in the past of
>whether replacing the sensors just because they are old does any good and I
>cannot remember what the conclusion was.  I hope to maybe get under the car
>tomorrow and finally do away with the sporadic CE lights! :)

I'll just mention what I have discovered with old oxygen sensors.

I had a Tbird Turbo that went 200K miles.  I changed the sensor on it when it was
recommended, at about 85K miles, and there was no change.  The car got up to 33 mpg
or so at cruise all the time I drove it.  So I figured that they don't wear, and
didn't need any attention.  Then, I heard from the list's performance gurus,
particularly Nick Chrimes, that they tend to slow down in their switching from rich
to lean as they age, and they should be changed after a certain period of time.

So, when the Lowrider started getting up in miles, around 150K or so, I started
paying particular attention to the variations in mpg that it got.  The mileage would
vary, depending on how I drove it, but would still average fairly good...22 or more
in town, and 26-30 on the highway, depending on length of trip, a/c usage, and
altitude of the highway.  After it got to about 220K or so, it did start to
fluctuate.  I never have gotten a CE light for the sensors, but they apparently slow
down in their ability to sense changes in the mixture of the exhaust over time, and
they had gotten so slow that mileage in town dropped to 15 or 16 mpg, but stayed
above 24 or so on the highway.  In town, the throttle gets moved much more, of
course, so the mixture fluctuates from cruising at 30 between lights to accelerating
from a stop, and then slowing for a light, with the throttle closed.  

           This is where I left off......

This poor mileage in town was the result of the sensors failing to sense the
different mixtures fast enough to vary the fuel flow.  They were wearing out, and
the mileage was suffering as a result.  I did not ever get a CE light.

I replaced them with the new sensors that came with theY-pipe group buy from the
SHOShop, and the mileage went back up to where it should be.

Cars last a long time for me, so someone else might need to replace them more
frequently.  The easiest way to tell is to keep track of fuel mileage, and
fluctuation of it with no reasonable explanation.

George