Originally Posted by FlyingForFun
And finally, a question. My car only has one spark plug per cylinder. It frequently sits at idle power for extended periods. But I don't recall ever having a fouled spark plug on my car. Why is that?
FFF
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Two reasons:
- Automotive engines have thermostatically controlled cooling systems, so the cylinder head remains within a closer temperature range - or outside of the head/plug temperature range that promotes carbon formation and fouling.
- Because your car has electronically controlled air-fuel ratio (mixture) so that it is not continually running way richer than it needs (a la Lycoming etc.) If it were to be running at 9:1 or so, like some aero engines do when full rich, it may be just as susceptible to fouling.
When I get plug fouling, I was taught the following (on a C152):
- run up to the green zone (>2000rpm) for a few seconds (5 or so), then recheck mags
- run up to the green zone (~2000rpm), enlean slowly-ish until it coughs, then full rich and re-check mags
- brakes firmly on, run to full power, full rich for 5 or so seconds, then re-check mags
- return to base if still outside mag drop limit