Engine ran rough at idle after heavy rain on approach

[Randy Johnson]

Shot an approach through a monsoon recently. Not an unusual condition during Florida summers. No turbulence just a lot of rain. After pulling into parking spot at ground idle the engine began to sputter badly. Didn't shut down on its own and there was no indication of a problem during powered up flight or post flight taxi.

Anyone else have this experience? Its a first for me. Have flown thru heavy rain before with no issues. Everything looked fine under the hood and Im about to go back and start her up now that she's dried out in the hangar. Want to make sure I'm not doing any harm with re-start.

Will check sump for water in fuel...any other thoughts?

[N3322G]

Aside from water somewhere - long shot, maybe density altitude - too rich?

[md11flyer]

Randy, did you run up the engine to 1800 rpm to see if the sputtering disappeared before shut down?
You might just have a fouled plug. How old are your ignition harnessess? Maybe some of the monsoon water
found a way to play havok with your wires. (you wouldn't notice a single plug missing above idle, but during taxi in
if your lower plug fouled a bit and the top plug was missing due to the water, you might get your symptoms.
Go ahead and start it up and if you still have the sputtering and if you have an engine monitor it will tell you where to look.
If you don't have a monitor, then do a normal runup and mag check and go from there. I think once you start up and clear the
possible fouled plug your symptoms will go away.

Gary

[Rick Langley]

[quote= Didn't shut down on its own

Hello Randy,
What did you mean by this? Pulling mixture would not stop engine? Switching off mags would not stop engine? Or just that the "roughness" did not stop until engine shutdown?

Rick

[Randy Johnson]

Meant the engine didn't stall on its own at low idle just ran rough.

[Randy Johnson]

As a follow up...fired up the engine 10 days later and no symptoms. Flown her several times since and haven't had any issues.

First and only time its happened since I have owned the plane.