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2002 chevy trailblazer_ls
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35 Posts
Discussion Starter · #1 ·
So I'm getting psyched up to change the spark plugs on my '02 TB and I read all the horror stories and hype about this and that going right and wrong and all the tidbits of information about this convoluted process and noticed that some people advocate disconnecting the battery before starting this endeavor. I'm wondering if this is so no Dumbazz tries to start the vehicle, not realizing the fat azz sticking out from under the opened hood would indicate some sort of maintenance was going on or is this to prevent some sort of calamity to the coil packs? The odds of someone trying to start my vehicle while I'm doing this, ranges from zero to darn near impossible, as the keys are in my pocket and I'm alone at work inside a locked 10' tall security fenced in area.
 

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2007 chevy trailblazer_ls
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1,422 Posts
I believe they have you disconnect the battery so the pcm relearns with the new plugs. But my 2 cents while you are there clean the throttle body for which you will need the battery disconnected.
 

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2002 chevy trailblazer_ls
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35 Posts
Discussion Starter · #3 ·
Job is a little more complex than I originally anticipated. I have to remove the air filter box and passenger front tire now. Oh and the inside edge of the throttle body is RAZOR SHARP and will cut right through a denim rag and index fingers. Don't ask how I know... It was black inside BTW.

Why remove the air box and tire you ask? Well, to find the throttle body bolt I dropped and that didn't hit the ground. Didn't see it drop at all, just felt it slip out of my hand and hit metal. Sure hope it didn't go behind that heat shield as those studs are way beyond getting the nuts off ( or at least way beyond getting those nuts back on).
 

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2002 chevy trailblazer_ls
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35 Posts
Discussion Starter · #5 · (Edited)
Good news and good news and not so good news...

Good news: I found the bolt on the first cross member :)

Good news: I'm done bleeding like a stuck pig. :)

Not so Good News: We don't have a feeler gauge in our tool box. :mad:
 

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2003 chevy trailblazer_ls
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5,268 Posts
yeah several post on spark plugs people have commented on the sharpness of that inner lip. I too slashed my finger.
 

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2002 chevy trailblazer_ls
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Discussion Starter · #8 ·
I'm done :excited:

Plugs 2 thru 5 of course were pretty easy and straight forward. #6 wasn't as bad as I thought it would be as it threaded in easily the first try. My problem with #6 was getting the old plug out of the hole. I was working blind and the mechanical fingers just didn't seem to want to find it. I didn't have a spark plug socket with the rubber insert so I applied two 1/4" strips of electrical tape to the socket, starting on the outside and wrapping inside so each piece covered 1 flat. It provided just enuf friction to hold the plug. I took that crappy little wire loom holder off to get to #1. What a piece of crap attachment system that is. If you lift on the holder and twist the little plastic heads with a screwdriver they twist out of the holes giving plenty of room to work. With 1-5, I used the mechanical fingers to twist the plugs into the holes figuring there would be little chance of cross threading. I didn't have a torque wrench that would read in/lbs so I guesstimated. Sort of glad I removed the air box as the depression in the windshield washer reservoir makes a great tool holder. After putting it all back together and connecting the battery I gathered up all my tools and did an inventory… they were all accounted for. I was also told to wait 5 minutes after connecting a battery before starting the engine. Not sure why that is but as I had already invested this much time, another 5 minutes would hurt. Started it up and lo and behold… no Check Engine Light. :woot::woot::woot:

I let it idle for a few minutes and drove it around the parking lot to the front of the building. So far everything seems fine.

I can't for sure tell how much time was spent on the actual changing of the plugs as I did waste time looking for fallen parts and tools we don't have and also I'm at work and being this is a power plant does demand a little bit of my time. I would say I didn't spend more than an hour of actual working time.
 

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2002 chevy trailblazer_ltz
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2,762 Posts
1st time I changed my plugs took 2 hour and thenI got faster and the last time(3rd)I did it in a hour!Had to change so many times because I put 4 tip Bosch in and hated them and bought the A/C plugs again!A/C always work the best in my Chevys(I tried almost all kinds in my 67 Camaro and A/C made it run so good!)
 

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2002 gmc envoy_sle
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1,380 Posts
I'm done :excited:

Plugs 2 thru 5 of course were pretty easy and straight forward. #6 wasn't as bad as I thought it would be as it threaded in easily the first try. My problem with #6 was getting the old plug out of the hole. I was working blind and the mechanical fingers just didn't seem to want to find it. I didn't have a spark plug socket with the rubber insert so I applied two 1/4" strips of electrical tape to the socket, starting on the outside and wrapping inside so each piece covered 1 flat. It provided just enuf friction to hold the plug. I took that crappy little wire loom holder off to get to #1. What a piece of crap attachment system that is. If you lift on the holder and twist the little plastic heads with a screwdriver they twist out of the holes giving plenty of room to work. With 1-5, I used the mechanical fingers to twist the plugs into the holes figuring there would be little chance of cross threading. I didn't have a torque wrench that would read in/lbs so I guesstimated. Sort of glad I removed the air box as the depression in the windshield washer reservoir makes a great tool holder. After putting it all back together and connecting the battery I gathered up all my tools and did an inventory… they were all accounted for. I was also told to wait 5 minutes after connecting a battery before starting the engine. Not sure why that is but as I had already invested this much time, another 5 minutes would hurt. Started it up and lo and behold… no Check Engine Light. :woot::woot::woot:
You could have also used a length of rubber hose to fit on the top of the plug. You shouldn't have to gap the new plugs and if they do need it, don't pry against the center electrode. Otherwise, job well done! :thumbsup:
 

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yeah i'm gonna change the plugs in my x GF's 2003 t-blazer LTZ in a day or 2.
heard that #6 is really hard to get to. same engine as mine in the rado but more cylinders. shouldnt be to bad right? any special things i should know now would be greatly appreciated before i start.
thanks in advance!
 

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2002 chevy trailblazer_ls
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35 Posts
Discussion Starter · #12 ·
I read all the posts here to get an idea as to what others faced and when I was ready I gathered all the tools I needed (oops, except for feeler gauges) and set aside several hours so I wouldn't be rushed. Take your time and if you decide to remove and clean the throttle body (easy job), be careful, as the bottom inside lip is RAZOR SHARP (trust me on this)
 

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I read all the posts here to get an idea as to what others faced and when I was ready I gathered all the tools I needed (oops, except for feeler gauges) and set aside several hours so I wouldn't be rushed. Take your time and if you decide to remove and clean the throttle body (easy job), be careful, as the bottom inside lip is RAZOR SHARP (trust me on this)
yeah i have to clean the TB and MAF while i'm in there cause it has 180k miles. it's been throwing the misfire #5 code, then the CEL started blinking.
i done the rado's cleaning before so i should be good but figured i would check here first.
 

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2002 chevy trailblazer_ls
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Discussion Starter · #14 ·
One thing that helped me was I started with #2 and worked back, replacing coil packs as I went (didn't want them laying around getting dropped and banged up). When I got #5 done and left the coil pack off and pulled #6 coil pack and replaced the plug and coil before putting #5 back on. Left me just a tad more room and increased limited visibility just a bit.
 

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2002 chevy trailblazer_ls
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Discussion Starter · #16 ·
Not sure about others but I pulled the plugs off the coil packs before I pulled them so they wouldn't be swinging around on their wires. BTW, I hate GM electrical clips.
 

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2005 chevy trailblazer_ls
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68 Posts
I just changed my plugs and didnt need to disconnect the battery. Started up fine and now runs like a champ. I used NGK Platinum tipped spark plugs and also installed a K&N air filter. It seems to have alot more power now.
 

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2005 chevy trailblazer_ls
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I read all the posts here to get an idea as to what others faced and when I was ready I gathered all the tools I needed (oops, except for feeler gauges) and set aside several hours so I wouldn't be rushed. Take your time and if you decide to remove and clean the throttle body (easy job), be careful, as the bottom inside lip is RAZOR SHARP (trust me on this)
How important is it to clean the throttle body? How often should it be done?
 

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2003 gmc envoy_slt
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7,190 Posts
I recently cleaned mine @ 38k. It was dirty but I had no idle problem and it ran the same as before the cleaning. Some do it every 30k and report much better running after. If there seems to be any engine shake at all when you turn on the A/C, clean it.:m2:
 

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2003 gmc envoy_slt
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7,190 Posts
Not sure about others but I pulled the plugs off the coil packs before I pulled them so they wouldn't be swinging around on their wires. BTW, I hate GM electrical clips.
I'm not a big fan either. I leave the connector on and just unbolt one coil at a time. I put the coil on top of the engine or propped on the side so it is not hanging by the wire.
 
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