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EGT -99 and oil pressure dead at start (Read 534 times)
Aug 14th, 2018 at 1:25am

Indaloamman   Offline
New Member
I love flying!

Posts: 2
When I last flew my Rotax 912UL in a Zenith 701 two weeks ago all was well with my Dynon D180.  Today when I went to start the motor BOTH EGTs read -99, and the oil pressure was blank--three hyphens.  In the interval I've only swapped air filters. No other engine involvements.

We've had some heavy rain, though my aircraft is hangared we are still in view of the ocean.  I wiggled both connectors at the back of the D180, no joy. 

I'm guessing that my troubleshooting should take the form of checking the EGT sensors and connectors--in my case they are knife edge and wrapped in heat-shrink.I have a spare EGT probe I can wire in for testing purposes.

Also make sure the ground to the engine is sound.

Not sure what to do about the oil pressure, because it is wired directly to the connector. 

Everything else functions normally--I did a short runup this AM and no issues with tach, oil temp, fuel sensors, etc.

Troubleshooting guidance appreciated.
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Reply #1 - Aug 15th, 2018 at 4:30pm

Dynon Avionics   Offline
Dynon Official
Dynon Technical Support

Posts: 13142
Hmm, nothing obvious is immediately coming to mind here. Those are on different connectors, and also have pretty different means of measurement. I'd definitely start with looking at grounding and wiring.

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Reply #2 - Aug 16th, 2018 at 12:52pm

reidvaitor   Offline

Posts: 617
-99 I have seen on my EGTs when there isnt a connection on one the connectors, red X when both. Im guessing maybe when you did something to the airfilter you moved the egt wiring enough to cause the 2 EGTs to lose connectivity.
I just replaced one of my EGT probes and right after doing that I started seeing very low CHT temps on the same cylinder. Turns out when I replaced the EGT wiring one of the wires on the CHT got moved, they are old and hence brittle causing the wire to crack or something enough that the probe showed incorrect temps. I determined there was an issue when I put a new probe in and the temps aligned with the OAT.
I would suggest a new (dry) probe on each connector, test each to see if there is a change- maybe you'll also see the issue at that point too.That will eliminate probes otherwise focus on the wiring as Support suggested.
follow back to EMS and see if the pins are loose in the connector as third step.
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