Bob,

In contrast to when the primary injector power is off, when the
secondary injectors are turned off and the cold switch on, the EC2
indicates staging is taking place normally at the staging threshold, in
my case at about 20 inches MAP.  The engine doesn't go lean after
staging is indicated, however. When idling with the secondary injectors
turned off and the cold switch on, the EC2 indicates no staging has
taken place.  Of course, what the EC2's staging data bit is telling the
outside world and what The EC2 is actually doing may be two different
things.  

Steve Boese
  



-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Bob White
Sent: Sunday, July 05, 2009 9:12 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Below staging

Hi Steve,

No offense, but I'm quite sure the EC2 doesn't know if the injectors
are powered or not.  The disable switches operate on the power leads to
the injectors and the EC2 pulls the other side of the injector to
ground to fire it.  There's no input to tell the EC2 whether power is
applied or not.  What it does know is that the cold start switch is
activated.  In Tracy's wiring scheme, that happens automatically when a
disable switch is activated.  You have to do it manually but it amount
to the same effect. Your description is exactly the way it is supposed
to work.

You might also note that with the engine warmed up and idling with the
cold start switch off, you can turn off the secondary injectors and the
engine will run fine whether the cold start switch is on or off.  The
fact that it runs fine with the secondaries off and the cold switch on
emphasizes that the cold start function doesn't double the pulse width
below the staging point.  That would deliver too much gas to the engine.

You mentioned that the staged indicator was on with the primaries off
and the cold switch on.  Did you notice if the staged indicator was on
with the secondaries off and the cold switch on?  I would expect that
it was.  I think that's an indication that both banks of injectors are
active even though below the staging point.  Only those injectors that
are powered through the disable switches will operate.

I agree, it's not absolutely necessary to understand exactly how the
various boxes work to use them.  I'm an electronics guy though and it's
of interest to me.  I didn't even think about the below staging issue
until Mark Supinski asked a question on the AeroElectric list about a
problem he was having using a single three way switch for the injector
disable function.  Turns out he wasn't activating the cold start either
and the engine would always die if he disabled the primaries.  That's
when it struck me that when cold start is active, both banks of
injectors have to be operating from the EC2 side to make injector
disable work even when below staging.

Ed Anderson isn't quite convinced I have it right either.  If I can't
convince him, I'll have to change my story.  Or, Tracy will come
back from vacation and straighten me out.  :)

Bob W.