Sometimes I can't run LOP smoothly.

Challenged

Challenged

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Challenged
There was another current thread on LOP ops, but I didn't want to hijack it. I typically run LOP in my plane (200HP IO360), and while I probably need to do more testing so I can provide more information, it seems like sometimes I can't run LOP without having the engine run rough. Other times, however, I can run LOP (using my EDM 830 as a guide) without any issues at all...engine runs nice and smooth. Does density altitude, etc... play any part in running LOP, which would help to explain why sometimes I feel like it doesn't work well? Or maybe it runs rough LOP @ a certain RPM and not others?
 
Aren't we supposed to richen the mixture until the engine smooths out? I realize it's more the old fashion way of leaning, but it works for me.
 
LOP operation
Climb untill wide open throttle is below 65 percent power lean to rough rich to smooth
 
But according to my engine monitor, sometimes I'll have to be 50 ROP in order to have a smooth running engine. I realize there's no red box if I'm below about 60% power, but what seems strange to me is the lack of consistency in the ability to run LOP. One day I'll go up and my engine monitor will show all cylinders 25 LOP or more, all is fine. The next time I go up I can't even get to LOP on all cylinders without the engine running rough, just doesn't seem consistent. I haven't tested it enough I guess, and probably need to pull my engine data or take some notes on the parameters while flying.
 
Challenged said:
But according to my engine monitor, sometimes I'll have to be 50 ROP in order to have a smooth running engine. I realize there's no red box if I'm below about 60% power, but what seems strange to me is the lack of consistency in the ability to run LOP. One day I'll go up and my engine monitor will show all cylinders 25 LOP or more, all is fine. The next time I go up I can't even get to LOP on all cylinders without the engine running rough, just doesn't seem consistent. I haven't tested it enough I guess, and probably need to pull my engine data or take some notes on the parameters while flying.
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Plugs and mags need to be in good shape to run LOP consistently in my limited experience. And yes, take notes including MP, FF and temperatures.
 
In addition, you probably need CLEAN injectors.
If they are old, you might consider getting tuned replacements; otherwise make sure that they get de-varnished during the annuals.
Only takes a little crap to mess up good low flow atomization and consistent charges between cylinders
 
I notice the same thing. I figure it's atmospheric conditions. It seems to me I have to adjust lop several times on a trip. (Usually 1000 plus miles) temperature probably has most to do with it though I'm thinking. Was on flying last weekend from North Carolina to florida. Probably 400 miles was over water. That seemed to be the most consistent even with a 10degree temp change from north to south. Got cooler heading south. Also the higher I fly fl250 the harder it is to get and keep right.
 
oldShar said:
In addition, you probably need CLEAN injectors.
If they are old, you might consider getting tuned replacements; otherwise make sure that they get de-varnished during the annuals.
Only takes a little crap to mess up good low flow atomization and consistent charges between cylinders
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^^^^ this
 
Clark1961 said:
Plugs and mags need to be in good shape to run LOP consistently in my limited experience. And yes, take notes including MP, FF and temperatures.
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That right there. Ignition is the most overlooked part of the whole engine. Everyone immediately blames the fuel system, thinking that if a mag and its plugs are firing then the system is at 100%. Personally, as a mechanic, I have found way more issues, and fixed way more issues, with the ignition system than with any fuel system.

When fuel acts up things can get ugly real fast. With ignition, it can stumble along for a long time until something finally quits.

Dan
 
sourdough44 said:
Aren't we supposed to richen the mixture until the engine smooths out? I realize it's more the old fashion way of leaning, but it works for me.
Click to expand...
Not with that engine. Read the John Deakin articles I linked in the other LOP thread earlier today.
 
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