Hi all,

I attempted a flight a few days ago but during the run-up while checking the mags I checked the right mag and the rpm drop was 250+ and the engine began running really rough. I thought maybe it may have been a fouled plug so tried to burn it off, but no luck. My mechanic checked the plugs and they were good. The last annual was done in June and no issues were found. I lean regularly and never had any issues. I am having another mechanic (the electrical expert) look at it but it won't be for a couple of days.

Any idea what may be causing this issue?

Run the engine on the bad mag for a minute or two and the shut down and pop open the cowling. Splash or spray some water on the exhaust stacks. You will very quickly learn which cylinder is the problem. That will help in troubleshooting. With your mechanic, you then check to make sure that the P-leads are correct so that you know for sure which magneto and hence with plug and ignition wire.

Thanks Kristin

I will give that a go

Turns out to be an issue with the mag, mechanic found the problem and replaced a couple of the components, all systems are go...