Its important to inspect the plugs you remove. This will help to identify other possible problems
Is there any damage to the plug
-Record what cylinder the plugs were removed from
-Is there any material stuck to the spark plug tip?
-Check the body of the spark plug for signs of cracks.
Dig a little deeper
- is it the correct spark plug for the application?
- What is the spark plug gap?
- were they tightened correctly?
- Any damage to the spark plug wire or coil boot?
Tune Up / Spark plug replacement SHOULD! not just be remove & replace the spark plugs
