Impreza WRX F4-2.0L DOHC Turbo (2004)
Spark Plug: Adjustments
ADJUSTMENT
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)
NOTE: Replace with a new spark plug if this area (A) is worn to "ball" shape.