O² sensor: performance, economy, smog...

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clay - 20 Jun 2007 19:58 GMT

All this talk about smog and O² sensors has me wondering...
How much does the O² sensor influence performance, economy, etc.?

My '83 245 has always been on the border passing smog. Rattles on
premium, and gets 17-18 mpg combined.
Several years ago, during a pretest, the mechanic replaced the O²
sensor... after stripping out the exhaust manifold and calling his buddy
to bring over a tap so he could chase the threads and put the new one in.
I have to think he put a generic pos sensor in it instead of one that
belongs.
Any reason to put a new one in, possibly having to repair/replace the
manifold if the threads are trashed, to try to improve economy, etc.?

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James Sweet - 21 Jun 2007 00:47 GMT

> All this talk about smog and O² sensors has me wondering...
> How much does the O² sensor influence performance, economy, etc.?
[quoted text clipped - 8 lines]
> Any reason to put a new one in, possibly having to repair/replace the
> manifold if the threads are trashed, to try to improve economy, etc.?

Easiest way to test is put a digital volt meter on the signal wire from it
with the engine hot, the voltage should be rapidly oscillating, centered
around 0.5V or so. If it's lazy or just sitting low, the sensor is probably
bad.

If the engine is pinging on premium then something else is wrong, the car
should run just fine on cheap 87 octane, though slightly better economy and
performance can be had with mid grade. Might be worth having the injectors
cleaned and flow tested, there's a place called Cruzin' Performance that I
hear good things about. If this is a daily driver you'd want to pick up a
second set of used injectors so you can drive the car in the meantime.

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