EGT Question

SuperCub

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Jul 23, 2012
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I am having an issue with one EGT indication. What can cause an EGT indication with engine off and cold to show around 1100*F ?
 

dynonsupport

Dynon Technical Support
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Really the only things that can cause a false high reading are a broken wire on one or both of the EGT leads, or wiring it to something completely wrong. 1100F sounds more like a break somewhere.
 

SuperCub

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Jul 23, 2012
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So I exchanged the EGT sensor and installed a new one. Now I am having a higher reading on the cylinder with the new EGT sensor. It is very noticable and was not like this before. CHT is all the same.
Will it settle somehow after a few hours? Or do the EGT sensors have different calibrations dependent on manufacturer, manufacturing date or whatever??
 

Dynon

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As long as the EGT is a type K thermocouple (if it's from us, it is), it should read identically as any other. Are they the same at ambient? You can also try swapping one with another to see if the difference is "real" or not.
 

airguy

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Swap the thermocouples on a couple cylinders, and see if the problem follows the swap - if it does then the problem is with the thermocouple - if it does not then you have a legitimate cylinder problem. That could be a leaking exhaust valve or one spark plug not firing, either will cause a rise in EGT. You could also have a partially blocked fuel injector (if your engine is injected) causing a lean mixture for that cylinder, which will raise EGT.
 

SuperCub

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Jul 23, 2012
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Ok, today I did the sby battery test on Version 6.0 and I can see on the datalog that the EGT´s are going down during this 45 minutes all the same.
When doing a Mag check, also in flight, the engine runs normal with increasing EGTs (all of them), this would exclude the spark plug thing.
Remains the injector. I have to swap the sensors to see. But before the replaced sensor was showing too low a EGT it was always inline with the others. Personally I suspect the sensor but a swap should show the truth.
 

SuperCub

I love flying!
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Jul 23, 2012
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52
Now some time past but I had the opportunity to observe everything.
EGT #1 shows lower than the others. Before they all were even. I swapped the sensors, even installed a new one, still the same. Swapped the injectors and still the same. Important thing is the EGT peak is at the same fuel flow on all four cylinders.
A position error for the EGT mounting is not probable because the first 60 hours or so the EGTs were the same.

Could it be the wiring, different resistance due to poor connections?
 
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