[Shotimes] BARO sensor

[Kevin & Cheryl Airth]

Adam:
Well, We get to mess with the DPFE which is MUCH more failure prone and
complicated than the BAP setup!!!
 Which brings up a bit of trivia that I have not figured out. Maybe someone
with a California MTX can help? If the car is a MTX with EGR does it have
both a DPFE and a BAP sensor? Or does it lose the BAP and use the DPFE like
all the ATX cars do?
Thanks!
.
.



> Good thing us ATX'ers don't have to deal with a BARO sensor.  ;)
>
> Adam
>

>   Damn, Kevin!!
>
>   That's a really good write up!
>
>   You can also use an oscilloscope or a good quality (read that high end
>   Fluke) digital multimeter to check the waveform.
>
>   I know... who has one of those lying around...  But they are more
readily
>   available than frequency counters.
>
>   Although I'm not certain (been too long since I have used one) but the
>   oscilloscopes that used to be used for ignition diagnostics might be
able
> to
>   display that high of a frequency.  Those are getting fairly cheap since
> they
>   are no longer useful.
>
>   Jim
>

>   Tim The Tool Man:
>   Great screen name!
>   That's a tough one to troubleshoot. It very well could be the cause of
your
>   lean running but then again maybe not? The easiest way is just to swap
>   sensor's. There have been several long term drivability problems that
were
>   finally found to be the BP sensor but no code was set. The sensor was
still
>   operating in the correct range of values but was not changing at all.
This
>   made the car drive OK at some engine speeds and loads and to be WAY off
in
>   other conditions. It's mainly used as an altitude compensation device so
> the
>   closer to sea level you drive the less of an effect a bad BP sensor will
>   have.
>
>    Do you have access to another sensor?
>
>    The sensor can be checked with a frequencies counter. Yea, I know who
has
>   one of these? Anyway at sea level you should be seeing around 160-170
Hz.
> As
>   you apply vacuum to the open port the frequency should decrease to a low
of
>   somewhere around 90Hz. The sensor has 3 wires. One is the 5 VDC supply,
one
>   is a ground and the middle pin on the sensor should be the changing
output.
>   I do have instructions for using a tachometer to read the frequency. Set
it
>   on 4 cylinder setting and you should see 4800 rpm with no vacuum and the
>   rpm's should decrease with increasing vacuum.
>   .
>   .
>
>
>
>   > What symptoms will I see (if any) of a bad BARO sensor?