weird o2 sensor readings? (mc'd urq)

[Michael S. Williams]

At 10:57 PM -0400 7/10/03, Nate Stuart wrote:
>  > the only thing i'd say to this is that the actual flow of gas is
>>  going to be proportional to the amount of air coming in through the
>>  plate, not the throttle body...  there will be a drop in pressure (or
>>  increase of vacuum) for a split second until the air fills the gap
>>  there, but that would create a temporary rich-running condition, imo,
>  > if anything...
>
>Right, there is a pressure drop, but it is in the intake tract before the
>throttle plate.

yes

>There is an equal pressure 'boost' relative to the
>previous pressure level inside the IM (post TB), until these pressures
>equalize across the entire intake system, and the low pressure 'wave'
>reaches the CIS flow plate.

there can't be any excess pressure going into the IM, cause there's
not enough air to go in there, that's where the excess vacuum comes
from.  you are equalizing the entire system (intake and IM), which
would cause an overall drop in pressure for that instant...

heh, i wonder if it would be theoretically possible to actually suck
air OUT of the intake manifold under this kind of circumstance, if
enough positive pressure was applied before all of this... but i
digress...


>  In that brief period of time you have more
>pressure at the intake valves (shorter path to the valves, than to the
>metering plate), therefore more air getting into combustion chambers
>before the CIS plate moves to provide more fuel.

hmm... i think we have to discard the measurement of boost and vacuum
for this thought, at least relative to atmosphere

so, the question, i guess, would be if there is more vacuum in the IM
before opening the throttle than in the intake tract... you would
think that there would be more relative vacuum in a closed IM,
because of the fact that the pistons and valves are sucking air in to
the engine, even if it isnt there...  so i guess that answersthat
question...

but on the other hand, all of the air in the entire engine is already
measured, so any air in the intake tract is already known by the car,
so even though there is a rushing in of air to the IM, that wouldn't
necessarily increase a lean running condition, since there would
already be fuel for it, as measured by when it entered the system in
the first place...

>  I have no physics or
>fluid dynamics background, this is just my visualization of what happens.
>
>I really don't have a decent way to explain what it is I'm theorizing
>here, so like I said feel free to flame away on this, and I'll try and
>describe my thoughts differently.

same here, but i like theory...
--
MswmSwmsW

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