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2006 gmc envoy_denali
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50 Posts
Discussion Starter #1
Hello,

around 115k on the clock engine runs strong and trans shifts great but over the last 2-4 weeks on cold start the envoy makes this noise.

The noise goes away after 2-5 min max of driving and again has power, has good shifts.

the only thing I have noticed other than the noise is that when the truck is in park at running temps the car Almost acts like it has a super minor cam. The idle is a needles width above 500 then drops to just slightly under 500 then fine then does the process again ever5-10 seconds.
It does not do this behavior when truck is on any forward or reverse gear only in park.

Any info would be greatly appreciated

thanks!!
 

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2006 chevy trailblazer_ss_ls
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1 Posts
sounds like an. exhaust leak. possibly broken exhaust manifold bolts which the LS engines are famous for
 

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2006 gmc envoy_denali
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50 Posts
Discussion Starter #4
I did a MAF and TB cleaner using CRC cleaners for both and the noise seems to have gone away. Not sure but with the amount of soot that came off of the TB I assume when it started it had a hard time adjusting A/F mixture.
 
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