I was reading Tracy's EC2Ainstallation guide pdf
  and ran across this illustration of the back side of
  a DB37 male connector on page 20 and on page 25 of the
  EC2 manual. Then I checked the position of pin
  1 on the female mating connector on top of the EC2.
  Opps!!! Something did not look right.

  Pin 1 was actually on the left on the EC2 and it was on
  the right in the illustration. In any even I changed the
  illustration and here is the corrected version.

  Might seem like a minor point to us old sparkies but
  a newbe might be more confused than he is already :)

  Paul Lamar
  Be VERY sure you are correct about this.Literally hundreds have
  been  built according to these instructions and no one has had a reversed
  wiring problem.  Note which side of the connector is referenced in
  the  drawing.
  Tracy

  That is not what I am saying. Both will wire correctly.
  My point is the illustration in the EC2 manual is disorienting.
  I have looked at  the EC2 PC board and the ground pins 19 & 37
  are on the right looking down on the EC.

  My corrected illustration also has the ground pins  19 & 37 on the
    right  when the mating male connector is plugged in and you are
    looking down on  top of the EC. If you  rotate your illustration
  180  degrees to orient  it the same as the connector on the EC it would
    be clearer. That is what  I did and re wrote the numbers so they
  are  right side up.

  Am I wrong about 19 & 37 being on the right side of the connector
      looking down on the EC2?

  IMHO it would help if you labeled the pin numbers on the top
      of the EC2.
  Paul Lamar

  Without looking, I was under the impression that the illustration
    showed the mirror image or the other connector.  I am not sure
    which  is illustrated, but in would be on one side of the
  connection  and  the other of the connector, thus placing the number
  one pin, et  al,  on one side looking at its "front" and on the
  other looking at its  back.  Made sense to me at the time......
  Chris    Houston

  The male D-sub min connector will only mate with the female
  D-sub min one way.
  Here are both illustrations.  Which do you prefer?
  Paul Lamar

    I see what you're saying but don't understand why you would be
    looking at the EC2  while wiring the connector.  Wire the connector
    according to the drawing ( either one )  and you don't need to ever
    look at the numbers on the EC2.  I would think dividing your
    attention between the two would only confuse builders.

    Tracy

    Well I am taking it a step beyond just wiring the connector.
    I want to make it intuitively clear exactly what is going on
    and what goes where.

    I am organizing things in separate wiring harnesses according to function.
    This makes it easier to understand and  deal with as each harness
    can be done one at a time. One simple step at a time.

    I have broken the job down to 5 harnesses. Starter alternator
    harness, Sensor harness, Injector harness, Coil harness and PCM
    harness. Since it is hard to get wires in more than about 4 or five
    colors this makes the job much easier. I have located some 12 wire
    color coded vinyl jacket cable for the PCM harness.

    Since I am using the the terminal strip break outs for the D sub
  min  connectors on the EC2 and PCM  It cuts the job down to one or
  two  days for the whole thing. It is also a lot neater and easier to
   trouble shoot and fix wiring mistakes.

    I will reveal the new invention next week when the prototype
    is done :)

    I have two buses on the top of the engine to feed
    power and ground to the coils and power to the injectors.
    The test switches are not implemented on this go around.
    Here is a picture. The goal is a visual inspection capability.

    BTW I bought Mike's RV4 so I will probably rewire that too.

    I am also working on a heat sink for the RX8 coils.
    Do you have a source for RX8 coil connectors?
    I need at least 8.

    Paul Lamar

  Seems to me like right brain / left brain. Illustration just
  rotated 180*. As long as it makes sense and the builder is
  watching the terminal numbers.

  Dale Davies

  Here is what it is going to look like. The break out board is going
  to group the 37 pin D sub min pins into harnesses. There will be a small
  computer on the board that will monitor all the CAS, injection and ignition
  pulses and their width and send the data to a PC through a USB
  interfaces to be recorded on the hard disk. This will give a
  complete black box type record of the engine performance for the
  entire flight. Including fuel used and RPM. This wil be an option to
  keep the cost down for the basic break out board.

  One glance at the data will determine if anything has failed in the
  main computer or the crank angle sensor. Sort of OBD II for aircraft
  computers :)

  Paul Lamar


The diagnostic ability will be a huge benefit.

Dale Davies

I agree. It should make it easier to tune as well
as all injector pulse widths will be recorded.
If it is running like crap at a particular RPM
you will see why but looking at the pulse width
change. The manifold pressure is pretty much a
function of RPM as the prop is known load.
If I am lucky enough to get an A to D in the BASIC
stamp I can monitor MAP directly.

Here is a preliminary sketch. I am still refining
the pc board layout. I have been through about a dozen
iterations so far. I have to get it down to 2.5" by 3.8"
to get a good break on PC boards. When I am done it probably
won't look anything like this.

Paul Lamar

This is coming together extremely well. I discovered a surface
mount pressure sensor that will fit on the board in the upper right
hand corner. The BASIC stamp has a built in 8 channel 10 bit A to D
so I will be able to correlate all of the injector pulse widths,
manifold pressure, RPM and the ignition pulses.

It will make a huge  spread sheet file  on the hard disk with data
second by second. The cost will be very modest. Just a few $100.
A black box recording of all engine parameters.

It will also make it much easier to wire Tracy's ECU's.

This will be a tremendous help to all you guys out
there tuning  Tracy's EC.

It is a lot of design and programming  work but I think it will
be worth it.

Paul Lamar