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03-04-2010, 01:49 PM #11
check your pvc valve and the lines going into the air box tube make sure nothing came off. id have a buddy rev the truck up so you can get next to the motor and pin point it
next would be to check the fuel trim and see if it is running richGM TECH
05 silverado shortbed
03-08-2010, 02:22 PM #12
I'll give it a look.. thanks for the help!
09-15-2010, 08:48 PM #13
- Join Date
- Sep 2010
I don't mean to hijack the thread, but I noticed it's been quiet for several months.
My 05 Avalanche 5.3 (stock) has made the same hissing sound just off idle since I bought it back in '07 with 34k miles. I even had the dealer listen to it. They said it was normal, but did clean the throttle body under warranty. I'm now at 85k, and the sound hasn't changed....except for something new I've noticed this year.
Under moderate acceleration I'm hearing a pulsing air/sucking sound somewhere between 2800 and 4k rpm. It's much more noticeable with the AC running, but can be heard with no accessories on. It seems to be in rhythm with the engine, making me wonder if it could be the intake gasket. Other than the sound, it seems to be running fine, no noticeable reduction in power or economy. No codes. At first I thought it might be the passenger exhaust manifold (seems to be coming from that side), but it doesn't tick or smell like exhaust under the hood. The sound isn't very loud, but I may be able to pick it up on video.
Thanks for any help!
09-17-2010, 06:50 AM #14
This engine has a TBI you said??
If so, check the gasket between the TBI and the intake.
02-02-2011, 09:07 PM #15
- Join Date
- Feb 2011
My 2003 Silverado 4.8 just started making the exact same sound as your video. Did you ever find the cause? I also have a slight whistling noise under moderate acceleration. 2000-3000 rpm. I noticed this today on my way to work. Thanks!
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