Hi Paul-

We've run into a puzzler with our EC2 setup & since Tracy is away on a
vacation for a few weeks, I thought I'd throw it out here & see if anyone
has any bright ideas.

The suggested wiring setup for the EC2 has switches that allow injector
banks (primary or secondary) to be disabled in flight should one of the
injectors fail.  The pilot rolls the dice and arbitrarily switches off
one of the banks -- either the engine smooths out, or the engine goes
out.
Keep trying until one figures out the position for smooth running.

I changed this to instead wire it to a single switch (pri-both-sec).
Figured its easier to reverse the position of a single switch if the
engine
stops, vs messing with 2 switches.

Here's the conundrum.  As part of our runup, it sure would be nice to
confirm each bank of injectors is working by going from both to pri, and
then from both to sec.  Seems like this ought to work too.  But, when
we try
this, what happens is:

     both to pri = engine continues running just fine.
     both to sec = engine dies.

Before anyone leaps up with "Staging" as the answer, we have tried
this at
widely varied rpms -- from idle to WOT.  Always the same results.

Sooo... in the absence of Tracy, anyone have any bright ideas??

** One possible reason.  In the manual, Tracy calls for the cold start
terminal to be tied to ground when either of the injectors is switched
off.
The manual indicates this is supposed to double the flow rate of the
remaining injectors to compensate for the missing pair.  I did not
wire it
this way (didn't have a 3-pole swich).  Have I just answered my own
question??  I was expecting to find the engine rpms reduce (since
there is
no doubling) but not just die.

Thanks everyone--

Mark (Rocky Mtn High)

Hi Mark;

A couple of quick thoughts.
Have you tired physically and electrically swapping the injectors?
The secondary injectors could also be gummed up.
Sorry, I don't remember your injector sizes and locations.

Do you know approximately what AFR you are running across your map?
(12.5-13? AFR)
Does the engine die suddenly?
any delay?
any hints of running rich/lean? (rough running/smoke/wet plugs/increased
rpm)
restart problems?

For the cold-start/3-pole wiring, is the goal to provide full voltage to
the injectors without PWM?
Depending on the injectors, that _might_ provide an increase over the
maximum rated flow - I would be surprised if it doubled the flow rate,
but it should get you something  50% to limp somewhere.  I can easily
see this stalling the engine near idle(too much fuel) or WOT(not enough
fuel) but help near 50% power.

Cheers
Cary