747 meet 730, 730 meet 165

[Clare Snyder]

Orin Eman wrote:
> 
> It probably wouldn't work.  Some sensors are fed thru a resistor from
> a voltage source (eg coolant).  You would end up with half the source
> impedance which would affect the voltage at the sensor.
> For example, when the sensors resistance is the same as the source impedance,
> the voltage across it would be half that of the voltage source.
> Half the source impedance and now the voltage across the sensor
> would be 2/3 that of the source... quite an error.  I wouldn't expect
> smoke from the ECU in this case tho'.
> 
> Some digital inputs might be OK, but you would have to reverse engineer
> the input circuitry to be sure.
> 
> For the resistor fed sensor, it wouldn't be too hard to make an
> op-amp plus transistor circuit to feed the second ECU.
> 
> > Has anyone any experience with running 2 ecms off the same
> > inputs?.  ie would they have enough "impedance" to share inputs?
> > or would they do something strange?.  The outputs would be
> > loaded independently of each other, as far as driving any loads,
> > it would all be run off a small motorcycle battery.  Was just
> > going to use some resistors (like 20 ohm for the injectors),
> > and hook up a ignition module with a 20 dummy load on it also.
> >   If this is unknown ground can anyone give me a list of things
> > that might go wrong.
> >   I can almost smell the smoke now
> > Bruce       Glad I scotch guarded all my Cone Shaped Hats
> >                  the other day.
Since most of the sensor inputs read VOLTAGE, not impedence or
resistance, it would likely work. You may want to use the reference
power from one ECU only, connecting ground and signal to both. If you
arre using a maf that outputs a variable frequency, unless it is
integrated as a voltage to read, it would be questionable.
-- 
                               _/\_
                       --|-----([])-----|--
                         S    0/  \0    B
         Alls well that ends well!! www.snyder.on.ca is back
                  E-Mail service is back to normal
                  To avoid bouncing E-Mail messages
                    Reply to Clare at snyder.on.ca
                                OR
Remove the R from clsnyder in my E-Mail Address to reply. Stop the
spammers!!!
It's hard to soar like an eagle when your stuck with a bunch of
Turkeys!!!