This issue has been briefly discussed before.
Specifically in May of 2009 by Don Walker with the
topic of "Fine Tuning"
2. Starting at about 6000 RPM, the RPM
display on the EM-2 starts dropping out.
By the time the RPM gets to 6500 or so it is
almost completely gone, but comes back when I
reduce the throttle. I have an optical
prop tach so I know it's speed
with some possible solutions further
down in the email
I have had an e-mail discussion
with Tracy and he says there may be an
Electrical noise problem. He wrote, "a cap and
a resistor on the injector line to the EM-2".
That's it, but no specifics or drawings. Anyone
have any thoughts on this? Right now I have
EC-2 line 17 hooked to line p3-6 on the EM-2.
It was suggested to do this to make the signal
stronger rather than have it just come via the
serial lines. By the way, I'm not an EE or
electronics tech so I really don't know what I'm
doing, just a guy who can usually follow
directions. I suspect there may be a common
cause to all this. Perhaps it is electrical
noise. It seems to be part of it. If the noise
problem takes care of some of this, great. Then
on to the remaining. My next experiment will be
to run the engine with only the Essential buss
on and see if anything changes. I only have one
Ground line off my battery to the Firewall
ground. If I remember correctly, 2 grounds run
off that to the engine and that's it. This
cutting edge stuff takes forever. Thankfully
it's not bleeding edge.
Don, Tracy...Ed....??? Was there a
resolution to this issue as I am having the same
thing happen to me. As I approach 6000 rpm the
display on the EM2 drops out to zero, but may
flash other values as well. When I pull back on
the throttle, the display to appear to become
happier and display what I think/hope is accurate
but will drop out again if I add power.
I was somewhat pleased that this
was described on an RV since often the first thing
folks will key in on for my project is the long
wire runs on my Velocity. Course, it could be the
long wire runs, but RV's do not usually have this
particular issue.
I also, like Don mentioned in his
original post, am not a EE, but am usually
somewhat trainable. I would have no idea of where
to start to address these issues....especially
such as adding a cap and resistor. Heck, I don't
even know what a cap is and just kinda sorto know
what a resistor is. Also, what "size" of these
items would be used and how would they be
used??????installed?????etc?????
I thought I would touch base here
before I considered troubling Tracy with a call
based in ignorance and frustration. I did search
the archives (as evidenced by finding Don's post),
however, determining WHAT to search for can be a
bit elusive as times.
I am really quite close to potential
first flight. Other than a few gremlins like the
one mentioned, I am pretty much left
with readjusting the toe in since the wings and
engine have been installed, setting the wing
incidences to the canard again and weighing the
thing...oh, and calling my local DAR.
Another gremlin for your
consideration. Again, concerning the EM2, I have
had the displayed numerals disappear. They will
then come back. I have RE-checked the wires and
all is as it should be, as it has been when I
checked in the past. It may be the rheostat connection
as it is the only thing I have not yet checked and
it sorta acts as if the rheostat has bee turned.
Finally, again, EM2, my EGT readings
are jumping all over the place. From maybe 300
degrees to 8500 degrees. It appears random and
jumps all over the place. Not surprising it trips
my "trouble light". Again, I have checked and
rechecked the wires and connections. My next
troubleshooting check will be to pull the sensors
themselves from the turbo manifold. I am
wondering if I placed the sensors too close to the
rotary exhaust (about 3 inches from the ports) and
I fried the sensors.
Tracy's tech day is Saturday,
Right???
Thanks in advance guys. I would not
have come this far without ya.
All the best,
Chris Barber
Houston
Velocity N17010