kgwilson Posted May 23, 2023 Posted May 23, 2023 My Gen3 3300A started running rough between about 2800 & 2950RPM & then after returning from a day at Tenterfield Mag 2 (RH MAG as seen from pilot seat had at least 1 cylinder misfiring. First I swapped out all 6 plugs one at a time with spares I had (used but going perfectly when replaced. I've got 36 of them). No change. Then I borrowed a lead tester & checked all leads. All checked out as good. Next I removed the distributor & it looked perfect but gave it a good clean & used some contact cleaner. Next started the engine, shut down Mag 1 & removed each plug lead 1 at a time. There was a RPM drop on each cylinder. Next got a new (genuine Honda) Coil from Jabiru & replaced the original (Honda knockoff) coil but still the problem existed. Mag 2 on runup 2000rpm had at least 1 cyliner misfiring. I took off & full power all good & the rough running was less noticeable but still there & full power S&L was 130 knots indicated at about 3200 running smoothly. On shutdown the idle mag check was good on both 1 & 2. The next thing I can do is swap distributor caps to eliminate that. My current thoughts are that I have a faulty HT lead or maybe 2 even though they all checked out using an HT lead tester. Anyone had anything similar of have any other ideas?
Thruster88 Posted May 23, 2023 Posted May 23, 2023 At work to isolate a cylinder ignition problems on Lycons a spray of paint on the exhaust headers 5 cm from the head, run engine in defect mode, left or right mag etc . Have someone watch the paint start to burn off. Stop engine,the defective cylinder should be obvious as less burned, colder. 6
kgwilson Posted May 23, 2023 Author Posted May 23, 2023 I tried the cold cylinder procedure as advised by an old LAME by starting the engine on Mag 2 & found cylinder 6 cold. I thought I'd found the problem but after replacing the plug that cylinder wasn't a problem but the miss was still there. This was when it began to get confusing. I think there is/was more than 1 problem. The new coil has solved one of the issues, now I have to find whether the other is the distributor or HT lead/s.
kgwilson Posted May 25, 2023 Author Posted May 25, 2023 Issue resolved. The coil was the only fault & the new one fixed it. The runup miss was due to about 30-40 engine starts to find the fault & no normal temp or RPM engine running. As mentioned the shutdown mag check was good after the first flight. Next flight was good. Runup no miss on either mag & smooth operation throughout the rpm range plus seemingly more power now. 6 1
Recommended Posts