EGT Sensor problem

[grmps123]

I have two Dynon EGT sensors attached to my Rotax 912 ULS. The Right sensor has started intermittently (but frequently) generating high temperature alarms. I switched the Left and Right sensor plugs and the problem seemed to migrate from Right to Left. I assumed, therefore, that the problem was with the sensor probe. On that basis, I bought and installed a new sensor. I haven't run the engine yet, but from cold the Right sensor is still showing off-the-scale high temperature.

Any clues, please?

Thanks...Keith Boardman

 

[Dynon]

If there was an issue with the wiring going towards the connection to the sensor, you'd get a random "floating" value which could be low, high, or something similarly random. If you disconnect the probe and connect the two sides of the EGT wire together you should see something close to ambient. That will let you test everything up to that connector.

 

[grmps]

Thanks. After further diagnosis I believe the Right sensor is displaying as the the Left sensor in the display. And vice versa. So I have chopped off a good sensor and replaced it with another good one, and I still have a bad sensor on the Left.

So two problems to fix!

Cheers...Keith

 

[s19flyer]

Let me know what you fond out. I'm having the same issues and was about to buy another sensor until I saw Dynon's response. Exact same think you are experiencing. I did find bad connections in the wiring to the spade connectors that were installed on the probe. I put two new connections on there and still have the same issue. I got the pre-fabricated wiring harness with my EMS and have double checked the wiring. Any ideas?

 

[13cz]

I am also having the same problem with my Lyc 4 cyl. I have replaced (swapped) probes and the condition persists on the same cylinder. I am suspecting a poor connection at the DB connector on the EMS Harness.
When I get back from work next time I will try the short circuit test suggested, but would appreciate hearing what you all found.
Ross

 

[jauen]

Similar problem here. #2 cylinder on left engine. Was spiking to max temp at startup. If I reset Lane A problem goes away. Now it will occasionally spike when advancing to full throttle from cruise, but it no longer spikes on startup. Cycling Lane A works every time. I'll check the EGT connections today.

 

[jauen]

I moved the EGT sensor to another cylinder and tested. It was certainly the sensor that was the problem. I replaced it. These things are not cheap. I only have 175 hours on it. I sure hope this was a fluke.

 

[ncq6c1eq4u]

Been dealing with exact same problem for some time.(RV-12 912 ULS 420 hours, D-180)  L & R reversed, erratic readings.  Most times EGT would perform normally about one minute after startup.  The other day, a -99 reading got me into the cowl and found a broken wire at the connector.  Put in new connectors and all was well for next flight but an hour later was getting -99 again.  Found that moving the probe wire around by hand would momentarily get reading into the positive range but would immediately turn negative.

Since it appears others have same problem, what is the cause and what is the fix?  In addition to the reversed leads, I found the crimping on the connectors suspect as I had previously replaced under-crimped EMS connectors elsewhere in the FWF area.  Proper crimping fixed the other issues; not so here.  Since engine start-up (heat? vibration?) temporarily fixed the problem before, what kind of discontinuity is going on here?

I don't want to throw parts at the problem but if this is something to do with the wiring inside the probe itself then I'm ready to install a replacement.

Jim
South Texas