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Power loss on one cylinder

Roo747

Member
Hey everyone, while I wait for the engine shop to get back to me I thought I would post on here and see if anyone has some input.

Went to go flying the other day and everything was normal with run up. Taxied out to runway, applied full power which stabilized for a second or two and then RPM dropped from 2700 down to 2200 and the EGT on cylinder #2 dropped about 400 degrees. I aborted take off and the EGT came back to normal.
Tried a full power run up and it stopped again at 2200 RPM and a big drop in EGT, about 600 degrees.

Any help or thoughts would be appreciated.
It’s an IO 375 M1S

Thanks
Andrew
 
Pull the prop through by hand and you will feel no compression where #2 would normally have resistance. Compression test on #2 likely would read zero or close. Perhaps a stuck valve? Cylinder replacement of #2 will resolve the issue but perhaps there is a less expensive alternative?

I have experienced this in flight. I was able to maintain altitude but engine shook plane significantly.
 
You need 3 things to make an engine run fuel, fire & air. If you disrupt any one of the 3, then it doesn't happen, or happens poorly.

- stuck valve
-clogged fuel injector

not as likely, based on the huge rpm & temp drop

-spark plug/wire/mag problem
-leaking intake

For troubleshooting, the compression test is a good place to start.
 
Adding Marvel Mystery oil to gas and oil helps with sticking valves. We HAVE to do this in our piston helicopters in the high heat of south Texas.
 
Injector

+1

My first guess. Second guess would be a partially sticking exh valve.

My guess as well. It happened to me on my IO-320 twice! Plugged injector. Thought sure it was a stuck exhaus valve, but no.
Ed
 
The #2 injector can be removed through the air inlet without removing the cowling. Worth a look. This has happened to me, quick clean and back in the air.
 
So, since my history is with carb's, how do you clean a plugged injector?

Educate me, please!

It happened to me and low CHT along with low EGT was the clue. I used acetone and a toothpick (acetone softens the wood some). Shave the tooth pick down so you can get it to feed in the hole by pushing/wiggling it in and rotating. The soft wood will deform and go in at the perfect size. It helps to dislodge the debris and can't hurt the brass.

If you hold the restrictor up to a light, you can see the debris.

Larry
 
Last edited:
Sorted!

Thanks for the replies everyone.

Pulled the injector, cleaned it out and runs like a top. Two full power runs (can't actually go flying today) with no hiccups.

Cheers

Andrew
 
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