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So I vented to you guys, lost some sleep last night
pondering this, wasted more time today thinking about it, and then went back to
the airport to check things out.
I had previously made all of the changes Tracy
recommended in case there was an issue with ground or supply noise. I didnt
believe that was the problem before, but with no better ideas went ahead and
made the changes. I'm now pretty sure that the electrical system is
solid.
Another possibility was that there was something
about the EFISM installation that caused this problem. Not sure how this could
be the case but the EFISM does have the capability to write to the MCT, so maybe
something was getting scrambled in the process?
I disconnected the EFISM. And the EFISM was
disconnected yesterday when this latest problem occured, so its not the cause.
Yesterday just before I quit in disgust I reconnected the EFISM and captured the
MCT to make sure it hadnt been corrupted. It looked fine and thats why it was so
puzzling.
Today when I started the engine it was clearly
still screwed up. I put the EFISM in EC2 monitor mode and immediately saw the
problem. This latest problem was due to the fact that my A controller injector
staging point had been corrupted and set to 12" MAP. The engine sure wont idle
on 4 injectors! I reset the staging point to where it belongs and the engine is
back to running as it should.
I now have 5 known episodes of spontaneous changes
to the EC2 (possibly more). The first time the staging point was erased and the
secondaries wouldnt come on. The next 3 cases (twice in the past couple of days)
the B controller lost its program (since I dont have a way to view the B MCT I
dont actually know whats happening here, just that the engine immediately dies
when I flip to B). And then this last episode with the staging point resetting
to 12". I say there may have actually been more cases because my engine has
never really ran well on the B controller after doing an A to B copy. But it
does run - usually.
So Ed asks is there an action or sequence of
actions that may be related? Well the common thread here is switching to B. I
ran this engine for about 20 hours of ground testing before I noted the first
instance of this occuring. And this coincides with when I started actually
flying the airplane - and routinely switching to B as part of my pre takeoff
checklist. Then I stopped flying about 4 months ago to make all of these changes
and further tune the engine. During this time I dont think I ever switched to B
and noted no problems. This past weekend I started prepping to fly and went
through my typical pre takeoff prep and once again problems. Started
troubleshooting by routinely checking the B controller and once again corrupted
the EC2, this time the staging point.
Since my most consistent indicator of a change is
corruption of the B MCT its hard to say for sure, but if i can force the staging
point screw up a few times by switching to B I'll be convinced. I should note
that my install is not standard for the EC2 PCM. I removed the A/B switch, Cold
Start switch, and Coil Test switch from the PCM and remoted them to my
instrument panel. Tracy noted this as an optional way to do things in my EC2
manual. I dont recall how Tracy implements these switches, but I assume they are
SPST to a pullup resistor on the EC2. I dont know if he has any circuitry to
de-bounce or noise filter the switch input? I dont even know for sure that this
is the cause but seems to be the most reasonable explanation at this point. Stay
tuned.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Wednesday, July 01, 2009 6:15
AM
Subject: [FlyRotary] Re: frustrating
couple of days
Mike, its got to be
frustrating to have it run well for a couple of months and just when you have
convinced yourself the problem is gone, it comes
back.
I presume there is
nothing (no action, sequence of actions) that you can think of having taken
recently - any different than you have done during the months the engine ran
well that you can think of. Nothing different perhaps in getting ready
for another flight?
Since the fuel map is
stored in non-volute memory, it’s hard to figure out how it is being
re-written or destroyed. Normally (as you know) access to EEPROM on a
chip is a rather non-trivial process. Since the A and B controller
are two different chips, I suppose there could be a problem with the B chip –
but, while that does happen, it’s pretty rare. Have not had one myself
(yet).
You are able to copy
over the A MAP to the B MAP and it apparently does the copy, but then
something causes it to be re-written with garbage. You do not have Auto
tune and I presume you do not attempt to change the B MAP – but it changes on
its own. It sounds as it the changes to B happen whether you have
selected B controller or not – is that correct. Or does it only happen
when you are using the B controller or can you
tell.
Ed
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mike Wills
Sent: Wednesday, July 01, 2009 12:10
AM
To: Rotary motors in aircraft
Subject: [FlyRotary] frustrating couple
of days
I havent flown my RV since a
couple of cases of lost data in the EC2 back in february. Spent the last few
months making a bunch of mods, some suggested by Tracy, others were
things that I thought might increase long term reliability. Also had to fix
leaking fuel tanks in the ensuing
period.
Been working up toward renewing
flight testing. Engine has been running really well for the last few months.
Thought that the problem was cured, though not clear how. Then on
saturday found that once again my B controller had lost all data. Engine
wouldnt run at any throttle setting on B. Restored the B controller by copying
A > B.
Last night after work ground ran
the engine for about 30 minutes at various throttle settings and it ran as
good as always. Also ran fine on the B
controller.
Tonight after work I fired it up.
Ran fine initially. After about 15 minutes noted some minor surging at a
couple of throttle settings below 2000 RPM. Also noticed that in this RPM
range where the mixture had previously been fine, my mixture monitor is off
the scale lean. Slowly got worse, to the point that it wouldnt idle at
what was previously a solid 1350RPM. Couldnt get it to run at all below 1500,
everything between 1500 and about 3000 RPM pretty rough. Everything over 3000
is fine. No idea what caused this change. I put the airplane away and walked
away in disgust. I'm back to where I was a year ago and I'm just about fed up
with this thing.
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