EMS Oddity

On the flight home from Boseman last week and on the trip to Iowa today, I noticed that my CHTs and EGTs (all 4 of each) were high and fluctuating pretty wildly(+/- 75degF per sec). The engine was running great and the fuel flow told me I was LOP and running normally.

Oil temp/press was normal. Voltage was normal but fluctuating slightly from the normal 14.2 V. Manifold pressure seemed a bit high in cruise.

All readings were rock solid and normal on take off, crazy(as above) in cruise(7500 msl on the way down, and 3500 msl on the way back), and stabilized/normal as I came into the pattern at KLVN where I waited out the thunderstorms. They were stable (and normal) all the way home from LVN to ANE a bit later. This flight was done at 2000ft msl.

So I was stable at low altitude/high power(takeoff), stable low altitude/low power(landing at LVN) and stable on the short hop home (low altitude/medium power). This leads me to think it is altitude related, as odd as that sounds.

I did try switching off each ignition in flight - with no effect.

I'll send this to Dynon support, but I know the gurus here like a bone to gnaw on over the weekend. I'd appreciate your thoughts.

Pete,
I had a similar problem with my Dynon D120. EGT readings were eratic. After Dynon replaced the unit (Free of charge), and considerable time troubleshooting, I noticed that when I turned the 496 GPS off the problem dissapeared? Turned out that the wire that went between the 496 and the autopilot was too close to the EMS sensor wires. None of these wires were sheilded wire.(RF) can do strange things.
Hope this helps.
Dick

Wow!

N661DJ said:

Pete,
I had a similar problem with my Dynon D120. EGT readings were eratic. After Dynon replaced the unit (Free of charge), and considerable time troubleshooting, I noticed that when I turned the 496 GPS off the problem dissapeared? Turned out that the wire that went between the 496 and the autopilot was too close to the EMS sensor wires. None of these wires were sheilded wire.(RF) can do strange things.
Hope this helps.
Dick

Click to expand...

Hi Dick,

I never would have thunk this would be the issue, but I did move my XM antenna for the flights where this was an issue. I will fly and see if it coupled to the operation of my 396. Thanks for the tip!

Could be a loose connector

I had a similar event with my VM1000 after flying it for over two years. Was cruising home on a 3 hour flight at 9500msl, when I noted that the fuel flow was jumping from 2-5 gpm, and the oil pressure was 0-25. Engine was running smoothly, fuel pressure was good, and all temperatures were normal.

Upon decent to 2500 in preparation to duck under the class C at home, the gauges returned to a more normal reading, but I no longer trusted them.

In the end, I found two spade connector crimps that weren't good -- one fell out when I cut the tie wraps off of the bundle.

After fixing the connectors, fuel flow and oil pressure are rock solid.

Not altitude

I did some testing today and it does not seem to be altitude dep. I am guessing a bad connection as noted above.....