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William D. Mulneaux
William D. Mulneaux, GM Service Technician
Category: Chevy
Satisfied Customers: 224
Experience:  20 years Experience in all fields of auto repair. GM certified
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How to replace spark plugs on 2004 chevy trailblazer

Customer Question

how to replace spark plugs on 2004 chevy trailblazer
Submitted: 9 years ago.
Category: Chevy
Expert:  William D. Mulneaux replied 9 years ago.

Good evening,

My name is***** to Just Answer.

To start with you need to remove the air cleaner resonator, this is the plastic piece that covers the top of your motor, it should say Vortec. There is an induction hose coming from the air cleaner to the resonator. It is corrugated and is attached by a clamp to the resonator. Now on the other side of the resonator loosen the clamp that holds the resonator to the throttle body. Unplug the air intake temp sensor and remove the bolts holding the resonator to the engine. Remove the fuel pressure regulator vacuum line and the breather hose from the valve cover port. Pull off the resonator, be careful, go slow, make sure you're not tangled in anything. These small guage wires are easy to break


1.) Intake air temp sensor

2.) Clamps

3.) Outlet hose to throttle bodygraphic

1.) Breather hose nipple, resonator

2.) Breather hose nipple, valve cover

4.) Bolts

5.) Resonator

Now you can access the coils that sit on top of the plugs, remove the screws that hold the coils in place and the coil connectors. Remove the coils.


1.) Coil connectors

2.) Coil mounting bolts


Now you can access the spark plugs. Remove them from a coll engine. Damage can occur removing plugs from a hot engine. Make sure you gap all of the plugs. would recommend AC Delco plugs.

Let me know if you need more info.

Good Luck,