When taxiing or idling on the ground for long periods of time, it’s possible to experience spark plug fouling, even with modern, fuel-injected aircraft engines running low lead fuel.
The way to prevent fouling during taxi is to aggressively lean your engine while on the ground by following the specific procedure in your POH or, failing that, by pulling the mixture control slowly back until the engine begins running rough and then enriching it slightly.
I experienced spark plug fouling in a Cirrus SR22 last week during Sun ‘n Fun, which became apparent when we did the mag check and the engine began running rough on the right magnetos.
We weren’t going anywhere at that moment anyway since a pair of large sand hill cranes had taken up temporary residence in the middle of the active runway.
We taxied out of the way to take care of the issue, which involved leaning the engine and repeating the mag check. With the spark plug fouling issue remedied, we were ready to enrichen the mixture to recommended takeoff setting and go flying.
As we taxied back toward the runway hold-short line there was just one problem. The cranes had flown off but in their place was a big old Florida coyote in search of a meal.
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