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2002 chevy trailblazer_lt
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Discussion Starter · #1 · (Edited)
I have an 02 Trailblazer with 118,000 miles on it. Here's what I've been dealing with: My TB has been idling rough for awhile now and occasionally it threatens to shut down when I come to a stop (especially when I first drive it after it has been sitting all night or all day when I'm at work). If I start it and let it run for a little bit before driving anywhere it will idle so low at times that it almost stalls...it will then catch itself and go back to a normal idle. It will do that the whole time until I put it in drive and go. There has been the occasional time when I come back outside after starting it and it will have stalled completely.
In order to try to fix it I have replaced the fuel filter, the cam actuator, camshaft position sensor and the spark plugs have been changed. After changing out the cam sensor we were told to disconnect the battery to allow a "reset" when we did that, the service 4WD light came on and now the 4WD drive won't work (fuse is not blown)!! It was fine before! I feel like my Trailblazer is pointing and laughing at me...does anyone have any suggestions?

Thanks for any help you can provide!
 

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2002 chevy trailblazer_lt
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37 Posts
Discussion Starter · #3 ·
Thanks for the link! I have had the throttle body sprayed out a few times, but I am going to try it this way...it can't hurt! I am getting a little tired of throwing parts at it and getting no results.
 

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2002 chevy trailblazer_lt
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Discussion Starter · #5 ·
And that was yesterday.....today is a different story! I took out the throttle body and really cleaned it....it seems to be running better but still rough! I haven't tried Seafoam yet, but I am wondering if I need to try replacing the O2 sensor..? Seems like there are a lot of Trailblazers with this rough idle...just curious if anything worked for anyone....I'm kinda at a loss~! :bonk:
 

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2004
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Did you remove the battery cable when you cleaned the TB? The truck gets programed to run with it dirty, then when it's cleaned the computer has to relearn. If you didn't disconnect the battery I'd try that. Otherwise maybe just give it a day of driving? :m2:
 

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2002 chevy trailblazer_lt
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Discussion Starter · #7 ·
Thanks for the advice...I'll try to be a little patient! I did disconnect the battery when I cleaned it (sigh) I just can't figure out what would make it idle so loud/rough...cleaning the throttle body seems to have really helped with the threatening-to-stall issue....and don't even get me started on the
4WD issue....I think part of my problem is that I just paid it off....isn't that when they start to have issues?? ;)

How often should the O2 sensor be changed?
 

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The O2 sensor is past it's prime if it hasn't been changed before now. But the engine monitor should indicate if it's bad. It can be tested if there is engine performance issues to cause it to be suspect. It's not good for the CAT either if the O2 is bad.
 

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Discussion Starter · #9 ·
Thanks! I haven't gotten any indications (service engine light) that they aren't working properly, but I guess I'll just go ahead and change both O2 sensors out...can't hurt it!
 
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