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2002 chevy trailblazer_ltz
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Discussion Starter #1
l have a 2002 trailblazer that I have owned since new. I changed the water pump 2 weeks ago. When I started the vehicle it developed a very slight miss. It doesn't happen all of the time and it only happens at idle. I retorqued the pulley bolts. There is no noticeable wobble or play in the pulley. It does feel like a miss not an out of balance condition. It has 160,000 miles. I changed plugs (110,000 miles on the plugs). If it is coils or injectors whats the best way to test without throwing parts at it.
 

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2004 chevy trailblazer_lt
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339 Posts
You'll need a code reader/scanner that will show misfire counts in order to help you track down which cylinder is acting up. Have you checked for any codes?
 

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Discussion Starter #3
I should have stated that there are no codes. I don't know if my scanner will show live data. I'll check.
 

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2002 chevy trailblazer_ltz
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Discussion Starter #4
Well, I did a lot of thinking. The more I thought about it, the vibration happened after I changed the water pump. Coincidence? I negleted to mention(and I forgot), that I also changed the cooling fan because it was cracked. When I watched the fan while it was running I noticed the fan had a half inch wobble to it. A new fan is on the way.
 

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Did you replace the fan clutch when you replaced the water pump? Those are known to go bad as well, and I would think it would wear out and cause a wobble/vibration (such as the one you are seeing) before a bolt on rigid fan blade would. If you decide to replace the fan clutch, do not cheap out on it. Go with one of the following brands - ACDelco, Hayden, or Behr (Behr might be labeled Mahle or Mahle/Clevit they are the supplier of the OEM part to ACDelco) I put a Hayden fan clutch on my 2004 TrailBlazer, for what it's worth.
 

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2002 chevy trailblazer_ltz
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Discussion Starter #6
The fan clutch was replaced a few years ago with a quality replacement. I can see the plastic fan is wobbling. The only things I replaced were the pump and the fan. Then I got what I thought was a miss. I believe now it is an out of balance issue
 
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