Shaun,
Below is a description of how a O2 sensor works, placement
(temperature), is critical.
The Challenge.
The level of pollutants in exhaust gas must be reduced. While
open-loop control systems for ignition and fuel management can improve
exhaust emissions,
further reduction in emissions is only possible by using catalytic
converters. These converters operate efficiently only if unleaded
gasoline is used and if
combustion is as complete
as possible.
How It Works.
The oxygen sensor is a measuring probe for determining the oxygen
content of the exhaust gas. Since the amount of oxygen in the exhaust
gas indicates
precisely how complete the combustion of the air-fuel mixture in the
cylinders is, it is also the best starting point for controlling the.
air-fuel ratio. The oxygen
sensor is strategically located into the exhaust system. The outside
surface of the ceramic measuring tube protrudes into the exhaust gas
flow, and the inner
surface is in contact with the outside air. A voltage is generated at
the interface which is proportional to the relationship between the
residual oxygen in the
exhaust gas and that of the surrounding air: When this relationship
changes, so does the voltage. This voltage is processed by an electronic
control unit (ECU)
into a control signal for influencing the air-fuel mixture through
controllable fuel injection or carburetor systems. The exhaust gas
composition is thus always
maintained at that level which permits effective
after-treatment by the vehicle's catalytic converter.
Design Features.
The ceramic sensor body is contained in a housing which protects it
against mechanical effects and facilitates mounting. The ceramic body is
made of
Zirconium dioxide. Its surfaces are provided with electrodes made of a
gas-permeable platinum layer. In addition, a porous ceramic coating has
been applied
to the side exposed to the exhaust gas. This coating prevents
contamination of the electrode surface by combustion residue in the
exhaust gas stream for longer
service life.
The Advantages.
Feedback from the oxygen sensor provides closed-loop control of the
injected quantity of fuel for optimum air-fuel mixture. . . enabling
virtually complete
combustion to take place. By providing closed-loop control of the
mixture, it becomes possible to use three-way catalytic converters to
achieve the maximum
reduction in exhaust gas emissions. In addition,
the engine runs smoother and is more fuel efficient.
> -----Original Message-----
> From: Shaun.Hendricks@bergenbrunswig.com
> [SMTP:Shaun.Hendricks@bergenbrunswig.com]
> Sent: Monday, August 03, 1998 5:00 PM
> To: dakota-truck@buffnet.net
> Subject: Re: DML: Exhaust question
>
> Here's some fanciful ideas on how I might try and satisfy emissions
> laws
> (if my state allowed) and still keep the evil dual exhaust:
>
> >The problem is that it also makes it very unlikely that one would
> pass an
> >emmisions test at that point , as well as voiding the warranty .
>
> Hmmm, couldn't you just make a single pipe that joined the two and
> take it
> in for emissions testing? Unbolt the thing after the testing is
> complete?
>
> >Ever see how many o2 sensors your Dak has ?
>
> Actually, no. But if the O2 sensors are an analog sensor, they
> would need
> to be either resistive or capacitive sensors. In either case, you
> should be
> able to daisy chain a "pair" together from each of the different
> exhaust runs
> and get the same signal ratio back to the Engine Computer.
> If they are digital sensors I think they'd need to have a
> mini-computer
> attached to them to handle the translation from analog O2 rushing by
> into a
> digital format. At this point you should just be able to reprogram
> them for a
> different flow rate, or get different sensors.
>
> >It can be done , but I would think if you are in an area that has
> stringent
> >emmisions laws that you would be screwed .
>
> Living in California, *I* wouldn't even try this on a street truck
> (You
> can't do anything out here). But if I was a track monster, I might
> try and
> rig up a quick disconnect system (maybe cotter pin nuts on the header
> plates
> or something) for a set of "track pipes" and a set of "street pipes"
> (I'm not
> a racer, so I don't know the rules; please pardon any ignorance if
> that
> violates any track rules). Given the "JBA: Jet Blower Accessory"
> post, I
> might even try to dump the exhaust directly downward in front of my
> rear tires
> ("Built in blowers]") : again *IF* I was a track monster. ^_^
>
> Shaun
> Tustin, CA
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