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2004 chevy trailblazer_ls
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Discussion Starter · #1 · (Edited)
I have an 04 Trailblazer (46K miles). It was great before I was t-boned in September. The body work took 2 months to complete and looks great. Unfortunately, when I picked it up, it idled rough/vibrated, especially when cold and between 6 and 700 rpm. I was hit on the passenger side and it caused enough damage that the floor boards had to be fixed along with the fender and doors. I have read thread after thread on this, and there seems to be as many fixes as there are problems. As my issue came up as a result of the accident (my opinion), does anyone have any thoughts on what might be the cause of my rough idle? The body shop checked both motor and transmission mounts. Their answer was it seems to be the exhaust. It is currently at the dealer, and they are telling me the same, but have no answer how to fix it except to add sound dampening parts. Oh, and it hasn't thrown a code.
 

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2003 gmc envoy_slt
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How is sound dampening material going to fix the rough idle? :confused: I would contact my insurance company and tell them it is not fixed.
 

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Discussion Starter · #3 ·
I absolutely am planning to call my insurance adjuster tomorrow. They guarantee the vehicle to be right, I plan to hold them to that. I also intend to call the service dept at the dealer in the morning and ask them to clean the throttle body assembly (excuse my ignorance if I have that wrong) as it seems that comes up as an issue quite a bit with this idle/vibration problem on these vehicles. Would the fact the vehicle sat for 2 months compound the gunkiness factor in the throttle body?
 

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2003 gmc envoy_slt
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I don't know about the two months, however, disconnecting the battery while doing the body work would have reset the PCM. So, if the t-body was dirty, that may explain the idle problem.:m2:
 

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Discussion Starter · #5 ·
I've read in these boards somewhere that the battery needs to be disconnected in order to reset the PCM (what does that stand for?), so will it need to be disconnected again to reset again after the throttle body is cleaned? And yes, the battery was most definitely disconnected during the body work.
 

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2003 gmc envoy_slt
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Power Control Module. It's the computer. It's considered a safety thing, to disconnect the battery.:m2:
 

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2003 chevy trailblazer_lt
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Lets not forget the exhaust system runs down the passenger side. check the pipes.:m2:
 

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Discussion Starter · #9 ·
Well the fun continues . . .
My trailblazer is still at the dealer. They've checked out the mounts, the exhaust system for damage, and anything else they could think of. They put it on the rack with someone in it so they could check for vibrations while it was in gear and running. I was hoping I could just get it and see what transpires, but late Friday afternoon the service manager called to tell me he found the water pump was unusually vibrating at low idle and found that there was something loose on it. That is going to be replaced in the morning. I'll pick it up tomorrow and see if it's any better.
 

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Well the fun continues . . .
My trailblazer is still at the dealer. They've checked out the mounts, the exhaust system for damage, and anything else they could think of. They put it on the rack with someone in it so they could check for vibrations while it was in gear and running. I was hoping I could just get it and see what transpires, but late Friday afternoon the service manager called to tell me he found the water pump was unusually vibrating at low idle and found that there was something loose on it. That is going to be replaced in the morning. I'll pick it up tomorrow and see if it's any better.
Becareful with that! The dealerships love to slap parts.
 

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My money is on the throttle-body needing to be removed and cleaned! There are at least a hundred threads on this issue and all turn out being a dirty throttle-body plate from inside the tb as we don't have a PCV valve and it gets pretty icky in there! Good Luck!
 

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I had a vibration at idle. The dealer service dept tried to tell me it was normal. I made the mechanic sit in another TB on the lot at idle for comparison. Then he agreed it was a problem. They replaced the motor mounts which fixed the vibration. One was broken. My TB had also been in an accident.
 

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Discussion Starter · #13 ·
This response is about a year late but for a little closure, I had the throttle body cleaned which helped a bit but didn't completely remedy the problem. The service manager wanted me to bring it back, but to wait and see if the problem would increase and be a little easier to diagnose. The entire time I was insisting that I wanted the mounts replaced, but was told that wasn't the problem. When I returned it, guess what the problem was. Yeah, the motor mount on the passenger side where the accident impact happened. The service manager was a good sport about it and told me he has lots of men tell him not to listen to their wives/girlfriends/sisters about what the problem is and most of the time the women are right. God didn't give us intuition for nothing. So my TB runs great now and has for almost a year. I love this car and hope to get at least 8 more years out of it. Considering it's 6 years old and has less than 60K miles on it, I think I may get to keep it that long.
 
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