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Don, It does sound like a noise problems to me and unfortunately it may be the
worst kind, ground noise. I'll attach a drawing of a noise filter for
the EM2 tach problem which may work as a bandaid but will not help the
EC2 map table dropping if that is what is happening. That is why I'm
not anxious for you to attack the problem that way. Did you happen to see the power distribution guidelines I suggested earlier?
BTW, did the dropout actually go to zero (mid scale on the EM2 display)
or to -127 which is the bottom of the scale on the EM2? There is a big
difference for troubleshooting purposes.
5800 static on a 76 - 88 Catto prop is not too bad on a warm day but if
you get more let us know. What do you get at top speed, WOT?
I am developing a backup CAS spec for the Renesis with the pickup mounted 90 degrees to the primary but it is not done yet.
Tracy (still in flood cleanup mode)
On Sun, May 3, 2009 at 8:02 PM, Don Wallker <drwalker@gbis.com> wrote:
Flying RV-8 N113BR 1.2 hours in the air, 3 flights, 35+ on engine
13B Renesis, EM-2, EC-2, RD-1C, Catto 76/88
Tuned intake, 17.5 in, Tuned exhaust 24 in
Flys like an RV, quietest plane around, long hushpower II and
tangential in series
1130lbs empty. Engine starts easy and runs smooth.
There are a few things going on with the airplane that that I am having
trouble with and don't seem to be making any progress on. Thought some
of you might have some thoughts.
1. Occasionally map addresses drop out. It hasn't happened in
a while, but 3 weeks or so ago, as I advanced the throttle there was a
rough spot. I went and looked at the EM-2 in track mode and sure
enough, address 43 was at zero. I manually programed in fuel and it
ran smooth again. Running through the Map addresses is now part of my
checklist.
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
3. Not getting full power. On the ground I can only get the
RPM to about 5800 static. Some others with similar setups are getting
6200 static. Once in the early days of running this, I could get 6100
on the B controller. Shortly thereafter, I foolishly copied A to B and
b starts acting like a. I can only get 6800 max RPM in the air,
midrange on the air-fuel mixture gauge. 8000ft, 40 degree day.
Additionally, B never works as well as A. When I make minor changes to
A and copy to B, it never runs as well. It is my understanding that
the only difference is there is no Temperature compensation and that
the coil disable switches only work on B.
4.High and unbalanced EGTs If I leave the mixture control just
a little below midrange, the EGTs stay pretty close all the way up to
5750 or so. If I enrichen the mixture the RPMs goes up 125 RPM or so,
but rotor 1 (closest to the CAS) starts climbing rapidly to about 1720
degrees or so and rotor 2 starts dropping off, down to 1450 or so.
Engine runs smooth. EGT probes have been tested. Pilot has been too
busy flying airplane to check if this is happening in the air. I'll
check on the next flight. Oh, no air leaks in the manifold. I've
checked several times. All rotor 1 intake manifold tubes are same as
rotor 2. Just a mirror image.
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.
A couple of successes:
My old style fuel pumps were starting to sound funny. In addition,
when one was running and I switched to the other, when the engine was
hot, the fuel pressure would drop, the engine cough and a few seconds
later the second pump would start pumping. I would run both for 30
seconds or so to get rid of the vapor lock before shutting off the
first one. I ordered and installed the new ones that RWS now sells.
This problem was less, but still there. Ended up insulating the
shielding around the pumps and this took care of it. Also the old
pumps were very noisy and whined loudly during all flight phases. Very
difficult to hear these new pumps. Nice!
My engine leaked a little oil from the top of the mount plate. I
had to take it apart when I realized that I had to drill a hole in the
engine case for the PSRU oil return. I didn't get it resealed
perfectly. It didn't leak much, but was a nusence. An engineer friend
told me how to fix it. Spray the area that is leaking with Carbon Tet
based brake parts cleaner and let it evaporate. Coat the area with
clean silicone. Pull a vacuum on the engine with vacuum pump. I
hooked mine up to the Crank Case breather tube going out the top of the
oil filler cap. I let it set for 24 hours and no oil leak! Now that's
nice!
I notice that there is a provision for a 2nd CAS to the EC-2. Has
anyone done that and how is it done and where to mount? I know about
using only aluminum for mounting the CAS.
I've come to understand the Mixture monitor and like it! It would be
nice if there was a wide range O2 sensor that gave more of an analog
response rather then the almost on/off reading that we now get. Anyone
know which one might work and if you are using one?
Thanks,
Don Walker
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