Justin,
At 5 hours of total time, my TSIO-550 developed a definite miss at high power/RPM. It would smooth out a bit if leaned, but the EGT and cylinder temp on #4 were definitely low at anything above about 2000 RPM. Engine idled smooth as silk; mag check at 1700
RPM totally good.
Short version of a long story: The valves on this engine have two springs, and the inner spring had broken, allowing
the #4 exhaust valve to “float” at higher RPM. I won’t tell you what all we tried to identify the problem, but it was “exhaustive.” The broken spring was not visible/could not be determined by just looking the cylinder. I found it by poking between the coils
of the outer spring with a piece of wire to determine that something inside was loose/moving around…and should not be…
Once the problem was identified, Ed Smith flew up with a home-made tool to compress the valve spring and remove the keepers.
He also brought a new spring (on a Saturday). Once the parts arrived, it
was less than two hours to have it up and running….but the diagnosis went the better part of two weeks.
Check this as a possibility, and I REALLY
HOPE you find the problem more quickly than I did mine!
Bob
From: Lancair
Mailing List [mailto:lml@lancaironline.net] On Behalf Of jwilless@itd-nc.com
Sent: Sunday, July 20, 2014 5:03 PM
To: Lancair Mailing List
Subject: [LML] Cold Cylinder
I have a Lancair ESP with a TSIO-550. Engine is very rough and low on power with #3 cylinder cold (100 degrees or more) on cht and egt while ROP. In cruise everything returns
to normal if I go LOP.
The injector o-rings looked okay when I inspected them. I sprayed the nozzle out pretty good with brake cleaner and shot a good amount of fuel out the spider and line. The injector
is clean.
Cylinder #3 acts normal at idle and run up. At full takeoff power the engine stumbles as #3 goes cold.
I've already done a visual inspection of all the clamps and couplings and conducted a soapy water soapy water test of the intake system.
There is a definite correlation between RPM and #3 going cold. Under about 2450 rpm ROP, #3 was smooth but a good 70 degrees colder than usual. When switching to LOP, #3 CHT
comes right up in line with the other cylinders as normal and I can increase the rpm. When #3 get's rough, egt drops lock a rock.
I tried using the high pressure fuel boost and modulating the flow with the mixture for a full rich condition but #3 stayed pretty cold.
Mags checked out in all phases ROP and LOP.
The #3 valves looked good with the scope and the compression was 72/80. The top plug looked a bit oily when I pulled it.