---------------------------------------------------------- Continental-List Digest Archive --- Total Messages Posted Mon 06/16/08: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 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 _____________________________________ Time: 06:45:03 AM PST US Subject: Continental-List: IO-240 B4B: Rough idle and left mag drop From: "FlyboyTR" 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 _____________________________________ Time: 02:23:16 PM PST US From: "Roger Bartholomee" Subject: RE: Continental-List: 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 _____________________________________ Time: 07:22:14 PM PST US Subject: Continental-List: Re: IO-240 B4B: Rough idle and left mag drop From: "FlyboyTR" 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 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message continental-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Continental-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/continental-list Browse Digests http://www.matronics.com/digest/continental-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.