1999 Escort L4-122 20L SOHC VIN P SFI: Spark Plug Specifications
5. Carbon-fouled spark plugs are caused by a fuel mixture that is too rich. These spark plugs can be cleaned.
6. Overheating damaged spark plugs are caused by engine overheating, incorrect ignition timing, or incorrect spark plugs. Replace these spark plugs
once the overheating condition is corrected.
7. Normal spark plugs have light tan or gray deposits on them.
8. Pre-ignition damaged spark plugs are caused by incorrect ignition timing, engine overheating, burnt valves, or the wrong type of fuel. Replace
these spark plugs once the pre-ignition condition is corrected.