Mailing List flyrotary@lancaironline.net Message #6917
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Rusty's O2 / EM2 problems.
Date: Tue, 30 Mar 2004 23:18:24 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
Rusty, I tested a new mixture monitor (small 2" instrument) and found that bar 5 (first green bar) comes on at .546 v  which is what I would expect.  Bar 10 (second red bar at top) came on at 1.1V.  This sanity checks with what I found when I used this meter in that bar 10 would usually not light even at very rich mixtures.   The EM2 was calibrated to be full scale at about .950 V.  
 
 I'm stick'n to my story.  Full output on O2 sensors is 1 V.   Don't know where your problem is but this should point you in the right direction. 
 
 Tracy 
 
Thanks for checking that Tracy.  My mixture monitor lights the 5th bar at .85V, and the 10th bar lights at 1.4V.  The EM-2 works exactly as you described, with essentially one step per tenth of a volt, giving full deflection at 1.0V.  I also looked up the specs for O2 sensors, and found that they are indeed supposed to be from 0-1V.
 
When I used this mixture monitor on the rev-1 version, I could adjust the mixture knob for full scale readings in each direction, so I can't see how it would have been possible for the O2 sensor to light the upper bars.  The only explanation is that something has gone wrong with my mixture monitor since I last used it.  I'll be testing that theory very soon, because I'll be installing it temporarily with it's own wire to the O2 sensor.  I'll be able to run either, or both together for testing.
 
I'm also starting to wonder if I got a bad O2 sensor, which is causing my EM-2 to show me bad data.  Since the EM-2 is calibrated exactly as it should be, that only leaves a bad sensor.  I probably won't get to do anything with it tomorrow, so you can forget about answering the phone, and get back to that fiberglass we love so much :-)
 
Cheers,
Rusty
    
 
 
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