A: (1) Check if the spark plug clearance meets the requirements.
(2)Check the lower part of the spark plug for contamination and carbon deposits.
(3)Check if the side electrode is damaged and the center electrode is leaking.
(4)Check if the spark plug insulator is cracked or damaged.
(5) Check if there is loose air leakage between the insulator core and the housing.
(6) Check if there is air leaks fir the spark plug gasket .
(7) Perform a flashover test.