Oxygen Sensor for 5KTQ

[Robert Myers]

 From http://www.forparts.com/Bos02update2.htm  The underlining and bold 
print below is mine and added for emphasis and were not present in the 
original.  There is a reference signal using O2 from the air.  We have seen 
this hashed over time and time again.  Here is your answer - direct from 
Bosch.  There is also a number of Bosch OXS drawings available from a 
variety of web sites in which the O2 path to the sensor element is clearly 
visible.

Unheated Thimble-type O2 Sensors (LS)

Bosch introduced this design in 1976 for feedback fuel control on 
automotive engines. The zirconia ceramic "thimble" is encased in a 
protective tube which extends into the exhaust manifold.  Slots in the 
protective tube allow hot exhaust gases to reach the thimble.  Reference 
outside air for the interior of the thimble comes from a hole in the sensor 
shell, or through the wiring connector.  Unheated O2 sensors rely only on 
the heat of the exhaust gases to reach operating temperature, therefore 
they might cool off while the engine is idling and revert back to a fixed 
air/fuel ratio setting. This type of sensor generally has a single wire 
connector, though some have two.

Heated Thimble-type O2 Sensors (LSH)

Introduced by Bosch in 1982, this sensor adds a heater element to the 
original design so that the sensor achieves operating temperature in 30-60 
seconds, instead of being heated by exhaust gases.  It has a separate 
electric circuit for the heater, so look for 3 or 4 wire connectors to 
distinguish this unit.  The heater reduces cold start emissions, as well as 
prevents the sensor from cooling off at idle.

At 12:08 PM 5/9/2005, Louis-Alain_Richard at computerhorizons.com wrote:

>*This message was transferred with a trial version of CommuniGate(tm) Pro*
>
>
>
>
>
>I remember a strange behaviour from a GM pick-up. When we had it
>oil-sprayed (for corrosion protection), the Check Engine light would lit
>just after, for a couple of days, as if the air surrounding the O2 sensor
>was contaminated by the oily fumes. This was an annual ritual, oil and CEL,
>for as long as we owned that truck. O2 sensor was of the 1 wire variety.
>
>Louis-Alain
>
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>Solid information on this is hard to find. Air must get in somehow. The
>outside shell shows no openings. And if the openings are so small that you
>cant see them . . .then they are subject to clogging also.
>The only way for air to get in is where the wires come out, or at the
>connector end.
>
>I brought up this topic hoping someone else knew more than me.
>Then again, maybe this is just an urban myth.
>
>SJ
>
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_____
Bob
Http://Chips-Ur-S.com

'95 urS6 Cashmere Grey
RS2 turbo/EM
Lucas/Delphi 37# injectors
Custom MRC software
Stromung Exhaust sans kitty
BIRA System 3 brakes
Custom brake lines
Centerforce clutch
100/130 watt H1 Eurolights
V1 w/ remote display
Ultranator alternator upgrade
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