Good suggestion from Al, Buly. I can't remember, do you
have an EM2? If so, check the MAP table with the EM2 and get familiar
with what the correction curves look like for your engine (no two
are exactly alike). Good idea to check it periodically for any signs
of data corruption if you think something is amiss. So far, Al's controller
is the only one that I know of that has had this problem. Not unit
specific because it has happened on 3 different EC2s in Al's plane so I have
concluded that it is something unique to his installation. I'd like
to get to the bottom of it and any other reports would be helpful.
Al and two other composite aircraft have reported mixture changes when
transmitting on the radio. Sometimes the problem is frequency
specific. I have identified a fix for this and it should be implemented on
any EC2 that exhibits this problem. A .1 uF capacitor is added directly
across pins 1 and 2 of the A controller MAP sensor to eliminate this problem (B
controller is not affected). RFI problems are a bitch to find
sometimes. There is already a capacitor across these two pins on both A
& B controllers. The one on A is only a couple of inches away from the
sensor on the circuit board but that makes all the difference. The part
must be physically close to the sensor to eliminate this RFI problem. All
future EC2s will have this added capacitor installed.
You can experience odd changes in the EC2 behavior for several other
reasons. For example, I have to change the mixture control from
the normal position when I do a hot start and take off because the air
temp sensor has been heat-soaked from heat in the engine room.
As it cools off on takeoff, the mixture gets richer and I then return the
mixture control to it's normal position.
Tracy (autopilot installation hell almost over)
----- Original Message -----
Sent: Friday, December 29, 2006 9:58
AM
Subject: [FlyRotary] Re: Yet another
non-event story
> >I noticed my mixture bar was going from lean to
totally
> desapearing. Turning the knob to full rich was not
enough.
> I saw this a few times.
Buly;
It would be
interesting to know if you had it previously tuned giving you
correct
mixture. I have had on-going problems with spurious changes
to
settings in the EC2. Carefully tune it one day, and find things
have
changed the next, and have had tuning changes occur during
flight. I have
noted changes in the mixture table, stage point
setting, injector pulse
width. Many, many hours spent trying to determine
cause, but as yet no
explanation. It has been assumed that it is
specific to my installation -
composite pusher with EC control box at the
firewall, EM2 acquisition module
at the firewall, display on the
panel. The problem is primarily with
controller A which communicates
with the EM2.
This may not be relevant to your installation, but it
would be worth paying
close attention to getting it tuned correctly, and
see if it stays that way.
Al
--
Homepage: http://www.flyrotary.com/
Archive and
UnSub: http://mail.lancaironline.net/lists/flyrotary/