How can plug fouling be remedied?

• A. By increasing engine temperature.
• B. By decreasing engine temperature.
• C. By changing spark plug wires.
• D. By changing fuel type.

Answer: (A)

Plug fouling happens when the spark plug surface stays too cool, so deposits like carbon or oil aren’t burned away and instead build up on the electrode. The remedy is to raise the operating temperature so the deposits oxidize and are burned off during normal combustion. By increasing engine temperature, you bring the spark plug into the range where it stays hot enough to burn off the existing deposits and prevent further buildup, restoring proper ignition.

Changing spark plug wires or fuel type doesn’t directly address the need to keep the plug hot enough to clean itself, and decreasing engine temperature would make fouling worse, since cooler operation tends to allow deposits to remain.