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2004 chevy trailblazer_ls
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Discussion Starter · #1 ·
Hey everyone! I've been stalking this forum for about a month now since buying a 2004 Trailblazer LS. There is a TON of awesome info on just about anything I need, and even a bunch of videos. I used several of these resources to change my spark plugs and clean the throttle body at about 91,500 miles. The throttle body wasn't horrible, but definitely needed a wipe down. The plugs were worn and needed the change as I thought. Now the truck idles much smoother, even when cold, and the throttle response is improved along with the power. It also seems to fire up quicker. It was definitely a worthy project for $50 worth of parts and what not. The only things I had trouble with were removing the coil from #1 (bumper end) and finding some oil on the threads of #6 (firewall end). I don't know everything about car design, but whoever decided to place that wiring harness immediately over the #1 coil needs to be beaten to death. They could've moved the harness 1 inch up and there would be zero problem. Other than that it was a very easy job, even on the #5 and #6 under the firewall. What do you guys make of the oil on the #6 threads? I've heard it could be a worn piston ring, worn valve covers, and/or harmless fuel deposits that occur sometimes. I really can't spend hundreds of dollars to fix anything right now unless it is absolutely necessary. Any feedback would be helpful. Thanks!
 

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2002 chevy trailblazer_ltz
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3,250 Posts
If the engine runs fine, and as long as there is not oil on the TIP or PORCELAIN of the plug, you should be fine.

BTW, are you sure it didn't come from when you actually removed the plug? Oily water can seep past the coil boot/seal and get into the spark plug well sometimes.
 

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2004 chevy trailblazer_ls
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2 Posts
Discussion Starter · #3 ·
If the engine runs fine, and as long as there is not oil on the TIP or PORCELAIN of the plug, you should be fine.

BTW, are you sure it didn't come from when you actually removed the plug? Oily water can seep past the coil boot/seal and get into the spark plug well sometimes.
I'm not sure; that sounds likely. This was the first time I've had to replace spark plugs on one of my vehicles so I'll admit I don't have mcj experience with the issue. It smelled like used oil. Fortunately there was not any on the porcelain or the tip, which I thought was weird. It does seem to run fine for now. Thanks for the reply!
 
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