OEM GMC Envoy Spark Plug

GMC Envoy Spark Plug Parts and Q&A

• Spark Plug
  25334145
  Q: How to ensure optimal performance by verifying the correct spark plug installation and inspecting its components on GMC Envoy?

  A:

  Checks must confirm a right Spark Plug has been installed since driveability problems can emerge from incorrect plug choices according to ignition system specifications. The selected Spark Plug must have appropriate heat range properties because lower heat can cause fouling while higher heat can result in pre-ignition and engine damage. You should check the terminal post for damage while ensuring its shape is intact and conduct stability tests by twisting and pulling it; the post should not move. Check the insulator for electrical charge movement to ground between terminal post and ground as well as inspect the Spark Plug boot for damage and the recess area of the Cylinder Head for moisture since saturated boots create arcing conditions. Pay attention to any insulator cracks which might enable improper arcing of electrical charges while verifying that the center electrode gap with the side electrode is not excessively broad since this hampers Spark Plug operation. Tightening the Spark Plug based on specifications matters because improper torque can generate operational problems but extreme torque can break the insulator. The insulator tip needs inspection for signs of tracking while the side electrode should be checked for wear or breakage simultaneously with evaluation of the center electrode's tightness or damage which produces a rattling noise. Check for electrode bridges that may result from deposits while examining platinum pads on electrodes when present together with excessive fouling conditions. The last step should involve checking the Cylinder Head Spark Plug recess area for debris since damaged or dirty threads may cause installation difficulties. Cylinder operation under normal conditions produces a brown to grayish-tan appearance with little white powder residue but carbon fouling shows itself as dry fleecy black carbon forming from excessive fuel mixture scenarios and fuel injector leakage or above-average fuel pressure or air filter obstruction or improper combustion. The combined effect of weak coils alongside worn ignition wires together with wrong Spark Plug gaps can cause fouling mainly during long periods of idling and slow speed conditions. The spark intensity suffers when deposit fouling forms because of oil, coolant or additives while producing a glaze over the electrode.
• Spark Plug
  12681663
  Q: How to replace spark plugs safely and effectively on GMC Envoy?

  A:

  Before starting the replacement of spark plugs you should switch off the ignition and then detach the Ignition Coils. Let the engine cool down first before you take out the spark plugs because this prevents seizing of Cylinder Head threads. Start by cleaning the Spark Plug recess to stop dirt from entering the Cylinder Head because it would contaminate the threads to prevent a correct fit of new plugs; use a thread chaser to clear any present contamination. New plugs require their Spark Plug gap measurement which must be compared against the specifications while necessary adjustments should be made before installing only sanctioned plugs since improper plug temperatures can destroy the engine. A round feeler gage must assess the gap of both new and reconditioned spark plugs before installation since handling might alter the measured gaps from their pre-set values. Use the provided thread chaser to insert the spark plugs into the Cylinder Head until complete seating occurs; avoid cross-threading by checking for seamless thread fit and do not tighten beyond 18 n.m (13 lb ft) torque specifications without using a thread chaser. Follow sequence by tightening Ignition Coil spark plugs up to 18 n.m (13 lb ft). Then reinstall all ignition coils.