Prizm L4-1600cc 1.6L DOHC VIN 5 (1989)
Spark Plug: Testing and Inspection
Spark Plug Diagnosis
NORMAL OPERATION
Normal spark plug operation will result in brown to grayish-tan deposits appearing on the portion of the plug that projects into the cylinder area. A
small amount of red-brown, yellow, and white powdery material may also be present on the insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels and lubricating oils with additives. Some electrode wear will also occur.
ENGINE MISFIRING
Engines which are not running properly are often referred to as "misfiring". This means the ignition spark is not igniting the fuel / air mixture at the
proper time. While other ignition and fuel system causes must also be considered, possible causes include spark plug conditions which allow the
spark voltage to reach ground in some other manner than by jumping across the air gap at the tip of the plug, leaving the fuel / air mixture
unburned. Misfiring may also occur when the tip of the spark plug becomes overheated and ignites the mixture before the spark jumps. This is