I was in the middle of auto-tuning the mixture in flight via the EM2 auto-tune feature; when suddenly at a particular table entry the mixture just kept going leaner and leaner, until the engine was losing significant power.  About the time I hit the mode switch to disable, I noted that the mixture bar showed full rich – topped out.  Clearly the O2 sensor was not functioning. I manually “repaired” that table entry, and continued on an enjoyable flight.

 

I later found that the copper wire from the sensor was broken at crimp splice I used to connect the O2 sensor lead to my wiring. (I basically don’t like crimp splices, but in a moment of impatience . . )There is only about an 8” span that is unsupported, but when I recently changed the sensor, I had not put any heat shrink strain relief on that connector.  The vibration broke it in about 10 hours of operation.  Previously I had soldered it and covered it with heat shrink and it was fine for 50 hours.  So I was reminded that some strain relief should not be overlooked, tie down that short span, and that an open circuit will give you a max rich reading.

 

I just got the latest updates in the EM2.  A couple things that didn’t work before, work now.  But I find that the “fuel used” readout is always blinking.  Is this normal?  It also seems that the calibration on some of the channels has changed – even though I re-input all the same calibration data I had used previously, I’m seeing some different values that I wouldn’t have expected to change.  Maybe this is a ‘Tracy’ question; if he comes out of hidingJ.

 

Al