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George H.
George H., ASE Certified Technician
Category: GM
Satisfied Customers: 18308
Experience:  15+years ASE Master W/L1 Drivability
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how do i replace the spark plugs on a 2004 gmc envoy xl v6

Customer Question

how do i replace the spark plugs on a 2004 gmc envoy xl v6?
Submitted: 6 years ago.
Category: GM
Expert:  George H. replied 6 years ago.

Hello I will help you with your question,


You remove the ignition coils first, there is just enough room to remove the back coils so work carefully




  1. Remove the air cleaner outlet resonator.
  2. Disconnect the ignition coil connectors (1) from the ignition coils.
  3. Remove the retaining bolts (2) from the ignition coils.

  1. Remove the ignition coils (1) from the engine.


IMPORTANT: Make sure that the ignition coil seals are properly seated to the valve cover.

  1. Install the ignition coil (1). NOTE: Refer to Fastener Notice in Service Precautions.

  1. Install the ignition coil retaining bolts (2). Tighten Tighten the ignition coil retaining bolts to 10 N.m (89 lb in) .
  2. Replace the ignition coil connectors (1).
  3. Install the air cleaner outlet resonator.



Then you can remove the spark plugs




  1. Turn OFF the ignition switch.
  2. Remove the ignition coils. NOTE:
    • Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.
    • Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.
  1. Remove the spark plugs from the engine.



  • Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.
  • Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine

  1. Measure the spark plug gap on the spark plugs to be installed. Compare the measurement to the gap specifications. Refer to Ignition System Specifications. Correct as necessary. NOTE:
    • Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.
    • Refer to Fastener Notice in Service Precautions.
  1. Install the spark plugs to the engine. Tighten Tighten the spark plugs to 18 N.m (13 lb ft) .
  2. Install the ignition coils.




Only use AC Delco spark plugs


Please let me know if you have further questions about this


Thank you