Today's Message Index:
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1. 06:45 AM - IO-240 B4B: Rough idle and left mag drop (FlyboyTR)
2. 02:23 PM - Re: IO-240 B4B: Rough idle and left mag drop (Roger Bartholomee)
3. 07:22 PM - Re: IO-240 B4B: Rough idle and left mag drop (FlyboyTR)
Message 1
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| Subject: | IO-240 B4B: Rough idle and left mag drop |
My IO-240 now has 425 hours. In the past it would only drop about 30 RPM on mag
check at 1,700 RPM. Even at idle speed there was almost no change in RPM, sound
or vibration when switching from both to L or R mag. It has always idled
extremely smooth at idle on either mag.
Three weeks ago I noticed the engine was idling rough. On the next flight, I had
about 120-150 RPM drop on the left mag (@ 1,700 RPM). The roughness at idle
has gotten worse. At idle, the engine will almost die when switched to the
left mag only...and sounds really ragged!
Here's what I have done so far:
Cleaned plugs, regapped to .019", pressure tested plugs, tested all eight spark
plug leads, checked engine timing (off by 2.5 degrees), removed and inspected
left mag. No pitting or issues noted with points. Reinstalled everything, timing
set to within 1/4 degree ("B" series engine is 26 degrees). I also removed
the injectors (for good measure) and give them an hour in the ultrasonic
parts cleaner.
Engine only drops about 100 RPM on left mag @ 1,700 RPM (better) but still runs
rough at idle and still will almost die when running only on the left mag at
idle.
I am at a loss at this point. The plugs are still within their wear limits. I
have ordered new plugs (Champion RHM38E) just to rule out a plug issue...even
though they pressure tested perfectly!
Your comments or suggestions would be sincerely appreciated. Thanks!
Travis :)
--------
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=188095#188095
Message 2
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| Subject: | IO-240 B4B: Rough idle and left mag drop |
The first thing to do is run the engine on the bad mag only and find the
cold cylinder. If you don't have 4 temp gauges spray wd40 on the exhaust
pipes to find the 3 hot ones. Then you can switch the plugs and even the
wires with one of the good cylinders. If this doesn't help I would chech
the compression and look at the exhaust valve if it is low.
Roger @ MD43 C150-E
-----Original Message-----
From: owner-continental-list-server@matronics.com
[mailto:owner-continental-list-server@matronics.com]On Behalf Of
FlyboyTR
Sent: Monday, June 16, 2008 9:43 AM
Subject: Continental-List: IO-240 B4B: Rough idle and left mag drop
My IO-240 now has 425 hours. In the past it would only drop about 30 RPM on
mag check at 1,700 RPM. Even at idle speed there was almost no change in
RPM, sound or vibration when switching from both to L or R mag. It has
always idled extremely smooth at idle on either mag.
Three weeks ago I noticed the engine was idling rough. On the next flight,
I had about 120-150 RPM drop on the left mag (@ 1,700 RPM). The roughness
at idle has gotten worse. At idle, the engine will almost die when switched
to the left mag only...and sounds really ragged!
Here's what I have done so far:
Cleaned plugs, regapped to .019", pressure tested plugs, tested all eight
spark plug leads, checked engine timing (off by 2.5 degrees), removed and
inspected left mag. No pitting or issues noted with points. Reinstalled
everything, timing set to within 1/4 degree ("B" series engine is 26
degrees). I also removed the injectors (for good measure) and give them an
hour in the ultrasonic parts cleaner.
Engine only drops about 100 RPM on left mag @ 1,700 RPM (better) but still
runs rough at idle and still will almost die when running only on the left
mag at idle.
I am at a loss at this point. The plugs are still within their wear limits.
I have ordered new plugs (Champion RHM38E) just to rule out a plug
issue...even though they pressure tested perfectly!
Your comments or suggestions would be sincerely appreciated. Thanks!
Travis :)
--------
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=188095#188095
Checked by AVG.
7:20 AM
Message 3
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| Subject: | Re: IO-240 B4B: Rough idle and left mag drop |
Roger,
Thanks for the reply. I have full cylinder management. There was less than 30
degrees between all cylinders while running on the left mag! I tried at idle,
1200, 1700 & 2000 RPM. I tried your suggestion prior to starting with the other
stuff.
I was sure I could find a cold cylinder. However...I have not checked for compression
loss......not sure why! On my last annual in September, all were 78/80.
Travis
--------
Travis Rayner
Mobile, AL
Skystar Vixen, N-789DF
Continental IO-240, Prince P-Tip Prop
ADI-II Autopilot
AnyWhereMap Navigation with weather
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=188217#188217
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