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Lane A indicates high EGT before start - up

  • Ross rynehart
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2 months 2 weeks ago #16811 by Ross rynehart
Ross rynehart created the topic: Lane A indicates high EGT before start - up
I went to go flying this morning and on doing the start up sequence the Lane A light was flashing after going through the start up sequence and the No 3 EGT was indicating full red - 1030 degrees. This was before actually starting the engine. No indication yesterday when flying of any issue with the EGT’s.

So far I have:
1. recycled the system
2. checked the sensor itself for any obvious signs of cracking etc, (but have not removed the actual sensor from the exhaust as I didnt think there would be much to see there)
3. undone the connector where the sensor cable joins before entering a loom with other sensors ( injectors etc) - all seems good there.
I now plan to:
4. check in the fuse box
5. check connections at the HIC harness connections
After that I am stumped? has there been any issues with the actual sensors themselves?

Any advice welcome beyond that.

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2 months 2 weeks ago #16812 by Bill Hertzel
Bill Hertzel replied the topic: Lane A indicates high EGT before start - up
The easiest way to eliminate the sensor is to swap it with one of the other ones that are behaving normally.
If the bogus reading moves to the other cylinder... Bad Sensor.
If the Bad reading stays on Cyl#3... The problem is something other than the sensor.

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2 months 2 weeks ago #16813 by René Caissy
René Caissy replied the topic: Lane A indicates high EGT before start - up
I had exactly the same issue on same cyl. Like Bill said, i swap the sensor and confirm that the problem was the sensor and not the cyl or injector or anything else. Rotech Canada ask me to send them de bad sensor for check and confirmed it was burn. I my case, nuts of exhaust was not tight enough and i suspect that it could burn my sensor.

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2 months 2 weeks ago #16816 by Bill Hertzel
Bill Hertzel replied the topic: Lane A indicates high EGT before start - up
Does the reading become normal after engine start?
Any Chance the Sensor is mounted with the Tip pointing upwards?

Moisture in the exhaust pipes will condense as they cool. This is normal.
If the tip is pointing upwards the water will migrate into the sensor.
Water in the sensor can act like a battery generating a current that the electronics interpret as high temperatures.
Once the engine starts, the high exhaust temperature will dry out the sensor very quickly.
Repeated drowning of the sensor will shorten its life.

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  • Ross rynehart
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2 months 2 weeks ago #16820 by Ross rynehart
Ross rynehart replied the topic: Lane A indicates high EGT before start - up
Thanks for all the info and ideas. I swapped it and it was faulty. I have a replacement on the way. Ridiculous Rotax price as usual - Aus$250.

For information, the engine has 310hrs and this was the first indication of a faulty reading.

cheers

ross

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  • richard Boslaugh
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2 months 2 weeks ago #16857 by richard Boslaugh
richard Boslaugh replied the topic: Lane A indicates high EGT before start - up
I Had the lane A go solid red in flight, was near home field so no problem.Dongle showed number 1 EGT bad, Replaced sensor and all is well. I now have a spare on board as a failure on a trip means wait to receive a new one or fly with one computer. Just returned from the Kitfox fly in. John had a 915 engine there and the EGT sensors are different design. The metal part containing the output wire extends past the mounting nut and then makes a 45 deg turn and extends a couple of inches. I have always wondered how much the wire on the type we have vibrates in the flow of cooling air coming in the front of the engine.

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2 months 2 weeks ago #16860 by Ross rynehart
Ross rynehart replied the topic: Lane A indicates high EGT before start - up
Hi Richard,

That's interesting information about the new sensor in the 915. I saw a 915 engine in one of the sti's on the Team Kitfox site - will be interesting to hear about the performance. And the flyin looked like fun. I will make an enquiry to the local Rotax dealer about those new sensors. They certainly sound like an improvement - I agree with you about the design improvement - I wonder if they are exchangable/compatable with the ones on the 912is?

On your point of carrying a spare - I also thought about that. I assume that the sensor is providing info to the computer to adjust fuel mixtures? Could be a problem in remote areas.

thanks for the infor.

r

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2 months 2 weeks ago #16880 by Bill Hertzel
Bill Hertzel replied the topic: Lane A indicates high EGT before start - up
Losing an EGT Probe is a Non-Event.
The EGT is informational only, it is Not used by the ECM to adjust Fuel mixture.

The Lane will display an alarm if the EGT goes out of range but will not take any action to adjust the mixture.
This is why the engine continued to operate normally when the EGT probe died.

If the ECM saw a cold exhaust due to a failed sensor and tried (incorrectly) to adjust the mixture in an attempt to correct the problem, that cylinder would have gone over-rich and started missing.
As it was, the ECM tried to isolate the bad injector on the apparently Cold cylinder and found that neither one resolved the problem.
The ECM concluded that it had no solution, and the Solid RED was displayed to get the pilot's attention so that he could take appropriate action.
In this case, the appropriate action was to continue to the destination and replace the probe when convenient.

The RED light made you look at the panel. Without it may have never noticed the Cold Exhaust.
You saw one EGT showing a cold exhaust, but the engine was still making full power.
The conflicting information should have formed the conclusion that the probe was lying.
I know it looked serious at the time, but it really was a non-event. Both ECMs were still operating.

If you saw the RED Lamp and the engine started missing, The Cold EGT reading would have informed you of the problem's location.
In either event, the ECM takes no action to adjust mixture other than toggling injectors.

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