glasairguy
11-28-2011, 12:21 AM
I have an interesting problem. I have about 350 hrs on my Lycoming IO-360-C1C and had some intermittent rough running that I have had problems diagnosing. I brought it to a couple A&P's who also could not diagnose it, mostly due to the issue happening only while flying, otherwise everything checks out. The engine seems to run rough only on 1 mag (left), although sometimes both will be affected when both are engaged, but when I single them out only 1 is running rough. I had the mags checked and they came out good. After a year of trying to get to an answer, I have replaced one mag with a E-Mag, replaced all the plugs and harnesses, rebuilt the fuel injector system, and have had everything else checked or replaced. I am now back to the remaining mag.
Last flight it flew perfect for about 30 minutes then started running rough. Selecting each mag didn't initially work, as both ran rough, then I reduced power and the e-mag cleared up so I flew it back on that one only. Strangely at this time the ELT also went off and since I couldn't reach the ELT to turn it off, I had to fly back for 20minutes with the thing transmitting. I am suspecting that the remaining old mag has a defective coil that is arcing once it gets hot. I think the arcing to ground could have affected the e-mag operation until I adjusted the power and then the e-mag timing adjustment circuit corrected. I am not sure how this could have impacted the ELT, other than it is located behind the exhaust a couple feet and could have been jarred by the backfiring. although I didn't think they were that sensitive. Does anyone have an opinion on this?
Last flight it flew perfect for about 30 minutes then started running rough. Selecting each mag didn't initially work, as both ran rough, then I reduced power and the e-mag cleared up so I flew it back on that one only. Strangely at this time the ELT also went off and since I couldn't reach the ELT to turn it off, I had to fly back for 20minutes with the thing transmitting. I am suspecting that the remaining old mag has a defective coil that is arcing once it gets hot. I think the arcing to ground could have affected the e-mag operation until I adjusted the power and then the e-mag timing adjustment circuit corrected. I am not sure how this could have impacted the ELT, other than it is located behind the exhaust a couple feet and could have been jarred by the backfiring. although I didn't think they were that sensitive. Does anyone have an opinion on this?