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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29588
Experience:  GM Grand Master Technician 2007. 14 years experience.
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how do i change the spark plug wires on a 2004 chevy trailblazer

Customer Question

how do i change the spark plug wires on a 2004 chevy trailblazer
Submitted: 8 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 8 years ago.

Welcome to Just Answer and thank you for asking your question. I look forward to helping you fix your vehicle.

 

I will try my best to help you and in order to do that, I need you to describe the issue in as much detail because I only know as much about your vehicle as you have told me in your post, so my answer will be based on what you have posted. Please include all the small details that may seem insignificant such as warning light or noises.

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Please feel free to reply as needed.

The spark plugs are under the large black box on top of the engine. There are 2 hose clamps, 2 bolts on the passengers side. Then once you get that off, you need to remove the coil packs. They take a 10mm socket. The spark plugs are under the coil packs.

Expert:  JOHN aka Eauto replied 8 years ago.

  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.

INSTALLATION PROCEDURE

NOTE:

  • 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.


  1. Remove the air cleaner outlet resonator.
  2. Disconnect the ignition coil connectors (1) from the ignition coils.
emove the ignition coils (1) from the engine.

INSTALLATION PROCEDURE

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.

 

 

 

Expert:  GM Tech (Cam) replied 8 years ago.
Object Number: 732051  Size: SH

  • Loosen the air cleaner outlet duct and air cleaner outlet resonator clamps (2).
  • Disconnect the electrical connector from the intake air temperature (IAT) sensor (1) .
  • Disconnect the air cleaner outlet duct from the air cleaner outlet resonator.
  • Disconnect the fuel pressure regulator vacuum supply from the air cleaner outlet resonator.
    Object Number: 730135  Size: SH

  • Remove the two air cleaner outlet resonator to engine bolts (4).
  • Disconnect the crankcase ventilation hose (1) from the valve cover port (2).
  • Remove the air cleaner outlet resonator assembly (5) from the engine.
  • Object Number: 725541  Size: SH


  • Disconnect the ignition coil connectors (1) from the ignition coils.
  • Remove the retaining bolts (2) from the ignition coils.
    Object Number: 725545  Size: SH

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