Spark Plug: Adjustment

WARNING: This page is about a different car, the 2003 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.

Clean the spark plugs in a sand blast type cleaner. Avoid excessive blasting. Clean and remove the carbon or oxide deposits, but do not wear away porcelain.

If deposits are too stubborn, replace the plugs. After cleaning the spark plugs, recondition the firing surface of electrodes with file. Then correct the spark plug gap using a gap gauge.

Spark plug gap "L": 0.7-0.8 mm (0.028-0.031 in)

Fig 1: Measuring Spark Plug Gap (L) With Gap Gauge

Courtesy of SUBARU OF AMERICA, INC.

NOTE: Replace with a new spark plug if this area (A) is worn to "ball" shape.