GM 19300875
Spark Plug

Executions must use the right Spark Plug to prevent drivability problems and should verify that the plug's heat range is correct to avoid fouling from cold plugs or pre-ignition damages from hot plugs. Check the terminal post and verify it has no damage along with checking its stability by gentle movements; it should not move. Inspect the insulator for flashover or carbon tracking because electrical charge moves between terminal post and ground while checking the Spark Plug boot for damage and examining the recess area of Cylinder Head for moisture which conducts arcing. Examine the insulator for cracks that might short-circuit electrical charge towards the electrodes while also checking that the center electrode distance from the side electrode matches product specifications (3, 4). Torque the spark plugs correctly since inadequate torque level can result in operational problems yet excessive torques may endanger the insulator. Inspect the insulator tip for tracking signs while checking the side electrode for wear or breakage and examine the center electrode for loose or broken components by shaking it to hear a rattling sound. Check for gaps (3, 4) due to accumulating deposits that close the space while also verifying electrode conditions (3, 4) regarding missing or worn platinum pads together with signs of excessive fouling. The proper installation of spark plugs depends on having a debris-free area inside the Cylinder Head Spark Plug recess where poor seating could occur. During normal operation the Spark Plug features brown to grayish-tan appearance with trace white powdery substances but carbon fouling develops as dry black soot from rich fuel mixtures among other causes such as leaking fuel injectors and excessive fuel pressure. Restricted air filters alongside incorrect combustion issues with reduced ignition system voltage and weak coils, worn ignition wires and improper Spark Plug gap and prolonged idling time all contribute to carbon fouling. Oil and coolant as well as additive deposits can decrease spark intensity since they develop glaze layers on top of the electrode.

Pre-set gaps may have changed during handling, and it is necessary to compare the measurement to the gap specifications from GM SPO Group Numbers.

Compare it to the gap specifications in the ignition system specifications.

Check for flashover, carbon tracking, or soot, which occurs when electrical charge travels between the terminal post and ground.

Confirm the correct spark plug torque, as insufficient torque can lead to operational issues while over-torquing may crack the insulator.

Turn OFF the ignition switch and remove the fuel injector sight shield.