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7suds(at)Chartermi.net Guest
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Posted: Mon Aug 19, 2013 6:34 pm Post subject: Engine Mischief |
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List,
I have been enjoying my Model 5 a lot this summer, even managed to squeeze in a flight into Airventure, but 2 weeks ago my daughter and I dropped into a small strip north of here to do some Blueberry Picking. When we were climbing out to leave the engine (912ul) lost power slightly, I pitched the nose down, pulled the power and pushed it back in and it was fine. Headed straight home (20 min flight) with no further problems, the change in power was so slight my daughter never noticed anything was wrong, but I noticed. Not sure why I did what I did, but it worked. (I also have an electric booster pump in-line like Lowell described with the switch next to the throttle, never even thought of using it). Not sure what it was I experienced, it almost sounded like I fouled a cylinder for a moment or the throttle slipped, but was a different sound than just reducing the throttle (not a slip of the throttle, my hand was on it). So last week I pulled the plugs, 50 hours on them, black sooted in front cylinders, golden brown in the rear, put in all new plugs, checked all plug wires. Pulled the carb bowls to look for debris, they were clean, visuals on everything else was normal. So I put it back together. Then last weekend I was giving my daughters friend a ride, we were in normal cruise attitude turning about 4500 and it happened again, I repeated the same procedure and it went away, again, my passenger never noticed anything wrong.
So, thinking it through and replaying the events in my head I am leaning towards what I actually experienced was dropping one of the ignition systems and the power loss was the 100 or so rpm drop.
Now trying to troubleshoot, prove / disprove my theory, wondering if anyone has had any experience troubleshooting intermittent ignition? Where to start, what NOT to do, Here is my thoughts,
1) Start with a thorough inspection of all ignition wiring, terminals, key switch remove tie wraps and bundling, chafe wraps etc, look for cracks, arcing etc.
2) Review manual for any ohm checks I can make on the coils, ignition systems, etc. Seeing the problem has been intermittent I am doubtful this will turn up anything. Seems strange that reducing the throttle and then increasing again cures the problem, broken wire, shaking?
3) If these steps turn up nothing I am considering taking it up, staying in the pattern at altitude and turning off one ignition to see if that is what I experienced, has anyone ever turned their ignition from both to one during flight? Anyone see any concerns?
4) After all that, if I am unable to find or recreate the problem, buy one ignition and change out one????
Appreciate any direction I can get,
Lloyd C KF 5 Outback
912ul IVO IFA Northern Mi
[img]cid:image003.jpg(at)01CE9D23.A6A4D6C0[/img]
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Jim Shumaker
Joined: 09 Jan 2006 Posts: 106
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Posted: Mon Aug 19, 2013 7:27 pm Post subject: Engine Mischief |
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I had vapor lock that was like that. Happened enough that I could predict it on a climb out in warm weather. Shielded the gascolator from the exhaust with a sheet of aluminum and have not had the same problem.
There is no problem with turning off one of the ignitions in flight. If you turn off both you should pull the throttle to idle before restarting.
Jim Shumaker
Kitfox III Rotax 912, 1200 hours
From: Lloyd & Lorrie Cudnohufsky <7suds(at)Chartermi.net>
To: kitfox-list(at)matronics.com
Sent: Monday, August 19, 2013 7:32 PM
Subject: Engine Mischief
List,
I have been enjoying my Model 5 a lot this summer, even managed to squeeze in a flight into Airventure, but 2 weeks ago my daughter and I dropped into a small strip north of here to do some Blueberry Picking. When we were climbing out to leave the engine (912ul) lost power slightly, I pitched the nose down, pulled the power and pushed it back in and it was fine. Headed straight home (20 min flight) with no further problems, the change in power was so slight my daughter never noticed anything was wrong, but I noticed. Not sure why I did what I did, but it worked. (I also have an electric booster pump in-line like Lowell described with the switch next to the throttle, never even thought of using it). Not sure what it was I experienced, it almost sounded like I fouled a cylinder for a moment or the throttle slipped, but was a different sound than just reducing the throttle (not a slip of the throttle, my hand was on it). So last week I pulled the plugs, 50 hours on them, black sooted in front cylinders, golden brown in the rear, put in all new plugs, checked all plug wires. Pulled the carb bowls to look for debris, they were clean, visuals on everything else was normal. So I put it back together. Then last weekend I was giving my daughters friend a ride, we were in normal cruise attitude turning about 4500 and it happened again, I repeated the same procedure and it went away, again, my passenger never noticed anything wrong.
So, thinking it through and replaying the events in my head I am leaning towards what I actually experienced was dropping one of the ignition systems and the power loss was the 100 or so rpm drop.
Now trying to troubleshoot, prove / disprove my theory, wondering if anyone has had any experience troubleshooting intermittent ignition? Where to start, what NOT to do, Here is my thoughts,
1) Start with a thorough inspection of all ignition wiring, terminals, key switch remove tie wraps and bundling, chafe wraps etc, look for cracks, arcing etc.
2) Review manual for any ohm checks I can make on the coils, ignition systems, etc. Seeing the problem has been intermittent I am doubtful this will turn up anything. Seems strange that reducing the throttle and then increasing again cures the problem, broken wire, shaking?
3) If these steps turn up nothing I am considering taking it up, staying in the pattern at altitude and turning off one ignition to see if that is what I experienced, has anyone ever turned their ignition from both to one during flight? Anyone see any concerns?
4) After all that, if I am unable to find or recreate the problem, buy one ignition and change out one????
Appreciate any direction I can get,
Lloyd C KF 5 Outback
912ul IVO IFA Northern Mi
[quote][b]
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_________________ Jim Shumaker |
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mikeperkins
Joined: 22 May 2007 Posts: 123
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Posted: Tue Aug 20, 2013 7:03 am Post subject: Re: Engine Mischief |
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Maybe before changing things out, see if you can get the problem to reoccur in a flight test above the airport and when it happens do a mag check. If one or two plugs from one mag had stopped firing, then shutting down the other mag would tell you a lot. But if the results seemed like a normal mag check, then you could begin to look elsewhere.
| - The Matronics Kitfox-List Email Forum - | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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_________________ Mike Perkins
Havana, Illinois
Model I, 532, B gearbox, GSC prop |
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7suds(at)Chartermi.net Guest
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Posted: Mon Aug 26, 2013 5:20 pm Post subject: Engine Mischief |
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Jim, Mike & Fellow Kitfox Listers,
An update on the engine Mischief,
Looking through the Heavy Maintenance manual and some on-line research I found other that experienced similar problems,
Dove into the wiring and discovered one of my grounding leads from one of the modules has a crack in the insulation, one trigger wire has the insulation worn through in one spot, and the 2 power leads from the ignition coils both had strands broke at the crimps of the OEM quick connects, probably from vibration. The ohm rating of these leads is listed to be 4.5 ohms, through the quick connect they were 6.5 ohms, once I cut the quick connects off I got 4.3-4.5 ohms. Also decided to check the trigger clearance while I was there, book says .012-.016”. My clearance is .009-.010”. More to come, in the process of repairing the wiring then I’ll tackle the trigger clearance.
Thoughts, advise welcome,
lloyd
From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of James Shumaker
Sent: Monday, August 19, 2013 10:26 PM
To: kitfox-list(at)matronics.com
Subject: Re: Engine Mischief
I had vapor lock that was like that. Happened enough that I could predict it on a climb out in warm weather. Shielded the gascolator from the exhaust with a sheet of aluminum and have not had the same problem.
There is no problem with turning off one of the ignitions in flight. If you turn off both you should pull the throttle to idle before restarting.
Jim Shumaker
Kitfox III Rotax 912, 1200 hours
From: Lloyd & Lorrie Cudnohufsky <7suds(at)Chartermi.net (7suds(at)Chartermi.net)>
To: kitfox-list(at)matronics.com (kitfox-list(at)matronics.com)
Sent: Monday, August 19, 2013 7:32 PM
Subject: Engine Mischief
List,
I have been enjoying my Model 5 a lot this summer, even managed to squeeze in a flight into Airventure, but 2 weeks ago my daughter and I dropped into a small strip north of here to do some Blueberry Picking. When we were climbing out to leave the engine (912ul) lost power slightly, I pitched the nose down, pulled the power and pushed it back in and it was fine. Headed straight home (20 min flight) with no further problems, the change in power was so slight my daughter never noticed anything was wrong, but I noticed. Not sure why I did what I did, but it worked. (I also have an electric booster pump in-line like Lowell described with the switch next to the throttle, never even thought of using it). Not sure what it was I experienced, it almost sounded like I fouled a cylinder for a moment or the throttle slipped, but was a different sound than just reducing the throttle (not a slip of the throttle, my hand was on it). So last week I pulled the plugs, 50 hours on them, black sooted in front cylinders, golden brown in the rear, put in all new plugs, checked all plug wires. Pulled the carb bowls to look for debris, they were clean, visuals on everything else was normal. So I put it back together. Then last weekend I was giving my daughters friend a ride, we were in normal cruise attitude turning about 4500 and it happened again, I repeated the same procedure and it went away, again, my passenger never noticed anything wrong.
So, thinking it through and replaying the events in my head I am leaning towards what I actually experienced was dropping one of the ignition systems and the power loss was the 100 or so rpm drop.
Now trying to troubleshoot, prove / disprove my theory, wondering if anyone has had any experience troubleshooting intermittent ignition? Where to start, what NOT to do, Here is my thoughts,
1) Start with a thorough inspection of all ignition wiring, terminals, key switch remove tie wraps and bundling, chafe wraps etc, look for cracks, arcing etc.
2) Review manual for any ohm checks I can make on the coils, ignition systems, etc. Seeing the problem has been intermittent I am doubtful this will turn up anything. Seems strange that reducing the throttle and then increasing again cures the problem, broken wire, shaking?
3) If these steps turn up nothing I am considering taking it up, staying in the pattern at altitude and turning off one ignition to see if that is what I experienced, has anyone ever turned their ignition from both to one during flight? Anyone see any concerns?
4) After all that, if I am unable to find or recreate the problem, buy one ignition and change out one????
Appreciate any direction I can get,
Lloyd C KF 5 Outback
912ul IVO IFA Northern Mi
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[quote][b]
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