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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
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