I got a response from one of the experts on rotax-owner.com.  Here's our exchange:

Here's the EGT/MAP trace I'm referring to in my last post.  Is my sensor measuring the wrong thing?  I don't recall ever seeing anything below ambient.  Ugh.

Well, the engine and plane were perfectly fine on flights this past Sunday and Monday, but then this happened on Tuesday...  Barely starts and even if advancing the throttle it won't get above about 780 RPM.

It looks like it's drawing only from the battery and never from either of the alternators.  That's not sustainable, right?

Thoughts?

Lots of flying the past few days.  3 flights: An instrument training flight to New Bedford Regional, a flight to Martha's Vineyard's Katama Airfield, and a local sightseeing flight to a popular mountain for hiking, Mt. Monadnock.

Me and Mike Emery on our way to Martha's Vineyard.

Smooth flight, even under the clouds.

Autopilot on and enjoying the scenery.

Heading out over the water to the Vineyard.

We'll be there in just a few minutes...

Lots of tiny boats in the harbor.

Short final into one of the three grass runways at Katama (1B2).  Pretty rough, so I'm not sure I'd fly in there again.  There's another airport on the island with smoother runways. 😊

Ellen and I doing some local sightseeing.

Me 😎

Mt. Monadnock in New Hampshire, which we've hiked several times over the years.

Sadie back in the nest.

The Oil Temp & CHT issues are FIXED!!  Last night I closely examined (and cleaned) all the sensor-related connections and found that the Oil Temp sensor ground wire into the spade connector was completely loose.  I could pull it out easily...  I did also find that the sensor wires were bundled together with the alternator wire for a few inches and that's a no-no (I didn't do it...), so I fixed that too.  I flew this morning and all was perfect!!

Nashua, NH airport.

Strong winds aloft!

Lake Winnipesaukee in New Hampshire.  Landed at Laconia Airport (KLCI) doing the RNAV 26 Approach.

Back home at 6B6.

I uploaded the engine data from the two flights on Saturday where the oil temp went crazy.  Interesting to compare them to two previous flights where everything was fine.

Good flight in April

Good flight in May

1st flight on Saturday.  Notice how CHT2 starts to go crazy when the oil temp starts to go into the yellow and red zones.

2nd flight on Saturday.

Went for a flight a couple of days ago and the oil temperature went through the roof (redline!).  It also happened a couple of flights ago.  It was 75F outside, so not crazy hot.

The only new thing is that I did an oil change about 5 flight hours ago using all standard Rotax parts and procedures.  Oil pressure is perfectly normal for the whole flight.  I did notice when viewing the video after the flight that one of the CHT measurements seems kind of wacky.

Some people on Rotax-owner.com said that the oil temperature was changing way too fast for that to be real.  Agree?  Thoughts?  The weather has finally gotten nice here, so I want to fly!

I'd really appreciate any ideas you'd have on this.  I sent this to Dean at Lockwood, but haven't heard back.

Full flight video:

Well, I'm definitely going to Oshkosh this year, but after much consideration, I've decided to not fly Sadie there.

With the crappy weather we've had over the last several months I've not flown as much as I thought I would and it's looking like a stretch to have my Instrument ticket by the time of OSH.  I really wanted to have that before flying the roughly 900 miles to get there.  Maybe I'm being overly conservative, but I consider that a virtue in flying, so I'm OK with disappointing some people with it not being there. 😎

I'll be there from Tuesday morning until Friday morning, so this time I WON'T miss the Sling Ding! 😁

Can't wait!!

When not flying in Sadie, I've been flying with my home simulator.  It's now a great setup using X-Plane, with a Garmin GTN 650 emulator from RealityXP on my iPhone and a physical device from RealSimGear emulating the Garmin GFC 500 Autopilot all running within the sim.  Using that with PilotEdge for practicing real ATC communications, I've got an amazing setup to make sure I have the buttonology (and comms) nailed down.  It even connects automatically to ForeFlight!

As you can see in this video it is super cool.  I'm still trying to get VNAV working though as most planes in X-Plane don't seem to support that autopilot functionality for some reason.  Apparently, people have gotten it working, but just not me yet...