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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.
On Sun, 5 Jul 2009 19:41:05 -0600
Steven Boese <sboese@uwyo.edu> wrote:
I'm, quite sure my EC2 knows whether or not there is power supplied to
the injectors.
With the engine warmed up and idling with the cold switch off, when I
turn on the cold switch the engine will run very rich and die. This is
expected, of course. Again with the engine warmed up and idling with the cold switch off, if
I turn off the power to the secondary injectors and turn on the cold
switch, the engine continues to run fine.
Once again with the engine warmed up and idling with the cold switch
off, if I turn off the power to the primary injectors and leave the cold
switch off, the engine dies starved for fuel. This again would be
expected.
Finally, with the engine warmed up and idling with the cold switch off,
if I turn off the power to the primary injectors and turn on the cold
switch, the engine continues to run fine. In this last case, the EC2's
staged indication indicates operation above the staging point even
though the engine is idling and the stage threshold has not been
reprogrammed using mode 7.
In both cases where the cold switch is on and one set of injectors is
not supplied with power, the engine runs fine from idle to full throttle
which is above the staging point but only 24 inches of manifold pressure
at my location.
In the end, I'm not sure it matters so much that we know exactly how
that crafty Tracy has accomplished the fuel injector backup function,
but it is important that we know how to use it properly for the way our
particular systems are set up.
Steve Boese
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Bob White
Sent: Sunday, July 05, 2009 5:27 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Below staging
Still catching up on messages! This is the last message that I've found
with this heading, and I think I can clear this up a little bit. This
isn't OFFICIAL from Tracy info, but it's what I think is happening.
Also, for now assume this is all for testing and there isn't really a
problem with the injectors. Reduces the number of "but on the other
hand's". :)
The EC2 doesn't know whether the injectors have power or not. It know
two things relevant to this discussion.
1) Is the cold start switch on or off, and 2) are we above or below the staging point.
If the cold start switch is on, then we should double the gas flow. If below staging, we can double flow by turning on the second set of
injectors. Now if cold start is on because you disabled one or the
other set of injectors, then both sets will be triggering at the same
pulse width as before, but only one of them will have power so gas flow
will be correct. This is really handy as we don't have to worry about
which set of injectors is turned off since with cold start on all of
them will be working.
If above staging, we would have to double the pulse width to double gas
flow. Again if one set of injectors is turned off, then you have 1/2
the injectors suppling twice the flow so gas flow is correct for that
situation also.
Of course it doesn't quite work right with different size injectors for
primary and secondary, so a little tweaking of the mixture control is
necessary.
Bob W. (Only 116 unread messages to go)
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