Hello
I wrote a HOW-TO on changing spark plugs. I took pictures while I did this as well. It looks like I cannot upload the pictures or Word Document until I post more. I tend not to post much as I find everything using 'Search'. So here is the text of the article I wrote. If anyone wants the actual word document with pictures send me a PM with your email address.
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So you want to change your spark plugs in your Trailblazer/Envoy with the 4.2L 6? I have a 2004 Trailblazer EXT 4X4 with the 4.2L 6 and did this a while ago. This is a very simple job that took me about 2 hours because I decided to snap some pictures. I will outline the steps I went through. I make no warranties regarding these instructions, I am merely offering up my notes as to how I did it. The tools needed are a straight blade screwdriver, 5/8 Spark Plug socket, 10mm and 13mm sockets, extensions and ratchet, anti-seize and new plugs.
The first step is to remove the Air Resonator and intake tube. There are two hose clamps, one on each side of the resonator that you remove. There are held on with clamps that use a straight blade screw driver. Once the hose clamps are removed you need to pull the hose off the resonator that goes to the air filter. Next there are two 13mm bolts on the passenger side that hold the resonator to the valve cover. Remove these. Next lift up the resonator from the passenger side and then pull the resonator off the throttle body. Store this, the clamps and bolts for reassembly.
Now you will have ready access to the coil packs and plugs. Each coil pack is held on with a 10mm bolt. I did one at a time to make life easy. Unscrew the 10mm bolt from the coil pack. I took a small straight blade screwdriver and pried up on the coil pack. Once the pack is loose I pulled it up and set it to the side. There is enough wiring that you can easily do this. Next use a 5/8 spark plug wrench and remove the plug. Use care that nothing falls into the spark plug hole. I put a little anti-seize on each of the plugs so removal will not be so hard next time. I gently tightened them down. If you prefer to use a torque wrench you would need to look up the specs.
Here is a shot of the coil pack pulled out of the way to gain access to the plug.
Here is my finished product, topped off with a K&N Cold Air intake. When I did this I ended up installing Bosch Platinum +4 plugs. The only reason is that is all I could find. I would have preferred Nippon Denso Iridium’s but they were not available. After the new plugs and K&N (My TB had 45,000 miles when I did this) I took a trip to Florida. I had a cargo topper on, 3 kids and my wife and I. I averaged 75MPH the entire trip and 19.5MPG. This is a marked improvement from where I started. Around the city it is averaging 15. While not stellar mileage, it is better. As for power it is really hard to say. I tow a 4,800lb RV trailer with the TB and the first trip is coming up soon. I am anxious to see if this helps. I was contemplating trying a TB spacer from Air-Raid as this is supposed to help low speed performance. I am very skeptical of things like that but if I can find one on eBay cheap enough I may just try.
If there is enough interest in this article I also did brakes on all 4 wheels. I may write that up as well. Thanks and hope this helps someone out.
I the moderator wants the Word document shoot me a pm and let me know how to post it.
Keith
I wrote a HOW-TO on changing spark plugs. I took pictures while I did this as well. It looks like I cannot upload the pictures or Word Document until I post more. I tend not to post much as I find everything using 'Search'. So here is the text of the article I wrote. If anyone wants the actual word document with pictures send me a PM with your email address.
***************************************************
So you want to change your spark plugs in your Trailblazer/Envoy with the 4.2L 6? I have a 2004 Trailblazer EXT 4X4 with the 4.2L 6 and did this a while ago. This is a very simple job that took me about 2 hours because I decided to snap some pictures. I will outline the steps I went through. I make no warranties regarding these instructions, I am merely offering up my notes as to how I did it. The tools needed are a straight blade screwdriver, 5/8 Spark Plug socket, 10mm and 13mm sockets, extensions and ratchet, anti-seize and new plugs.
The first step is to remove the Air Resonator and intake tube. There are two hose clamps, one on each side of the resonator that you remove. There are held on with clamps that use a straight blade screw driver. Once the hose clamps are removed you need to pull the hose off the resonator that goes to the air filter. Next there are two 13mm bolts on the passenger side that hold the resonator to the valve cover. Remove these. Next lift up the resonator from the passenger side and then pull the resonator off the throttle body. Store this, the clamps and bolts for reassembly.
Now you will have ready access to the coil packs and plugs. Each coil pack is held on with a 10mm bolt. I did one at a time to make life easy. Unscrew the 10mm bolt from the coil pack. I took a small straight blade screwdriver and pried up on the coil pack. Once the pack is loose I pulled it up and set it to the side. There is enough wiring that you can easily do this. Next use a 5/8 spark plug wrench and remove the plug. Use care that nothing falls into the spark plug hole. I put a little anti-seize on each of the plugs so removal will not be so hard next time. I gently tightened them down. If you prefer to use a torque wrench you would need to look up the specs.
Here is a shot of the coil pack pulled out of the way to gain access to the plug.
Here is my finished product, topped off with a K&N Cold Air intake. When I did this I ended up installing Bosch Platinum +4 plugs. The only reason is that is all I could find. I would have preferred Nippon Denso Iridium’s but they were not available. After the new plugs and K&N (My TB had 45,000 miles when I did this) I took a trip to Florida. I had a cargo topper on, 3 kids and my wife and I. I averaged 75MPH the entire trip and 19.5MPG. This is a marked improvement from where I started. Around the city it is averaging 15. While not stellar mileage, it is better. As for power it is really hard to say. I tow a 4,800lb RV trailer with the TB and the first trip is coming up soon. I am anxious to see if this helps. I was contemplating trying a TB spacer from Air-Raid as this is supposed to help low speed performance. I am very skeptical of things like that but if I can find one on eBay cheap enough I may just try.
If there is enough interest in this article I also did brakes on all 4 wheels. I may write that up as well. Thanks and hope this helps someone out.
I the moderator wants the Word document shoot me a pm and let me know how to post it.
Keith