Spark Plug: Installation: Notes
WARNING: This page is about a different car, the 2005 Jeep Wrangler. However, it is still accessible from the selected car via links, so may be relevant.
Always tighten spark plugs to the specified torque. Over tightening can cause distortion. This may result in a change in the spark plug gap, or a cracked porcelain insulator.
When replacing the spark plug and ignition coil cables, route the cables correctly and secure them in the appropriate retainers. Failure to route the cables properly can cause the radio to reproduce ignition noise. It could cause cross ignition of the spark plugs, or short circuit the cables to ground.