> Hi all-
     >
     > While trouble shooting my electrical system this
     > weekend, I found I have
     > fallen victim to the EC-2's ability to power itself
     > 'backward' via the
     > fuel injector control / power lines.  Yes, Tracy
     > does warn about this
     > behavior in the installation manual.  And yes, it
     > does drain one's
     > battery very effectively.
     >
     > His recommended solution is to put on-off switches
     > for both the primary
     > and secondary injector pairs.  His logic is this
     > allows one to disable
     > an injector pair if it is misbehaving, and at the
     > same time prevent the
     > backward EC-2 power phenomenon mentioned above.  I
     > am not a fan of this
     > solution - I wired my system with a single switch
     > primary-both-secondary.  I figure if I have injector
     > problems, I don't
     > want to be flipping a pair of switches trying to
     > find the right
     > setting.  There is comfort in knowing I need only
     > flip a single switch
     > either up or down to disable which ever pair is not
     > working.
     >
     > Which brings me to the title of this email --
     > namely, what kind of diode
     > to use.  I figure putting a diode into the circuit
     > will prevent reverse
     > current flow to the EC-2 without forcing me to add
     > or change switches.
     > I know there are plenty of EE types in the group, so
     > perhaps someone
     > could educate me on how to select an appropriate
     > diode for this
     > application.
     >
     > Thanks,
     >
     > Mark
     > -------------------------------
     >
     > Maybe I don't understand where you intend to put the
     > diode, but I don't
     > think it is a "reverse" current; but rather is in
     > the same direction as the
     > normal power to the injectors.  So a diode may not
     > be your solution.
     >
     > Al
     >
     > This is your typical injector driver circuit adapted
     > from a Megasquirt
     > schematic. The possible position of the diode is
     > shown.
     > The current is several amps peak so chose a diode
     > that can handle it.
     > --
     > Paul Lamar ...No rotor no motor.


    Paul
    The example ckt has the diode backwards; no injector
    current can flow. For an application with a diode in
    series with the load, a Shottkey diode would be a good
    choice. They will have a lower forward conduction
    voltage drop than a conventional diode.
    regards, Robert

    Right you are Robert. My mistake. Try this although I don't know how you
    are going to get it into Tracy's computer.
    In this case a diode with very little current capacity
    is needed.

    --
    Paul Lamar ...No rotor no motor.


I gather that the injector controller transistors are inside the EC-2
computer?

BTW, I concur with Tracy..  I prefer separate switches for the
injectors, just like for ignition or fuel pumps or any other system
where dual systems can/should provide redundancy..  Orient both switches
so that "up" is "on," and "down" is "off."  Easy to figure out what's
going on, and eliminates the possibility of any single switch failure
from killing the engine.


Regards,

Matt-


"I gather that the injector controller transistors are inside the EC-2
computer?"

Yep.