Spark Plug: Inspection

Disconnect the spark plug cable from the spark plug.
NOTE: Pull on the spark plug cable boot when removing the spark plug cable, not the cable, as it may be damaged.
Using the spark plug wrench, remove all of the spark plugs from the cylinder head.
NOTE: Take care not to allow contaminants to enter through the spark plug holes.
Check spark plugs for the following:
1. Broken insulator
2. Worn electrode
3. Carbon deposits
4. Damaged or broken gasket
5. Condition of the porcelain insulator at the tip of the spark plug
  
  Fig 1: Illustrating Spark Plug Components
  Courtesy of KIA MOTORS AMERICA, INC.
Check the spark plug gap using a wire gap gauge, and adjust if necessary.
Standard Spark plug gap : 1.0 - 1.1 mm (0.039 - 0.043 in.)

Fig 2: Checking The Spark Plug Gap
Courtesy of KIA MOTORS AMERICA, INC.
Re-insert the spark plug and tighten to the specified torque. If it is over-torqued, damage to the threaded portion of cylinder head may result.
Tightening torque

Spark plug : 20 - 30 N.m (200 - 300 kg.cm, 15 - 22 lb.ft)

NOTE: When replacing the spark plug, use the genuine parts which have resistance.