EGT Flucutations after setting Lean Of Peak

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1

HI all. Could not see anyone else with this issue but let me know if covered already. I have a normally aspirated SR 22 G5 with 700 hrs that has had no issues other than venting oil occasionally, even when below 6 quarts, something still haven’t figured out and maintainer says is normal. Anyway…

Recently, when setting lean of peak 50 degrees, within about 20 seconds, the EGT’s will change. In the image which was at 10 000 ft, i had set the last cylinder 50 degrees cooler than peak about 20 seconds before. It appears that cylinder 2 and 6 became richer, whist 1 became leaner. Also fuel flow a bit higher than i would expect at 10 000. I have had partially blocked/gummed up..injectors before. Which i would suspect on cylinder one this time, except that it fluctuates after setting the mixture.

Anyone had anything like this before? it is due for its annual in a week or so as well.

Thanks.

cirrusegt
cirrusegt1920×3410 1.18 MB

2

This is the classic “magneto timing is off - more on one mag than the other”.

Solution is to check the mag timing with a magneto synchronizer, to make sure both fire at the exact same time.

3

Thanks Paul. Is that something that creeps in? Everything was fine for 10 months, just started about 2 flights ago. (Been runnning it rich of peak since it started happening til i sort it out.)

4

Just spoke with maintainer. He suggests next flight, do a magneto check in the air when magentos are under load. If there is a problem say with the ignition leads, i will see a rise in cylinder temp as that cylinder gets richer due to unburned fuel. Or a problem with a magneto itself.

5

Magneto timing drifts, at different rates. Usually I will check the mag timing every 6 months, especially if I see a stair step pattern in the EGTs. New mags drift a lot at first, then settle down a bit.

Adjusting the mag timing requires a mechanic’s over sight. Just FYI.

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