Acceleration buzz/rattle

[brsexton]

This problem has been around for a good while, just now remembered to post about it. Anyway, I have the Ecotec and when I am accelerating and the RPM's get around 3200 RPM I hear a slight buzzing/rattle noise then once it passes 3300 or gets below 3200 it goes away. I have put the car in N and park and reved it to 3200 and it does not make the noise. Its only when I am accelerating in Drive. Sometimes it does not do it at all. I ask a friend and he said it might be spark knock, but thats not it at all. This sounds like something is loose. I have checked under the hood to see if anything is loose and I can't find anything. I was just wondering if you guys would have any clue what I could check. I might take it in, but I already know what its going to be "sorry we could not duplicate problem". Any info would help

[Naich]

if it sounds like an electrical buzz coming from your stereo, you have a loose ground somewhere in your stereo system. Other than that, I'd need to know more about it to help you.

[brsexton]

This noise is coming from under the hood. I am pretty sure this rattle/buzz is caused by the vibration of the engine once it reaches 3200 RPM, but I am unable to find anything loose. Also its really hard to figure out becase it won't do it while the car is in Park. The car has to be in drive. I read my service manual last night and it said that an acceleration rattle could be caused from loose torque converter bolts :unsure: . Which I guess could be the reason it only makes the noise when the car is in gear. If you guys have any more idea's please let me know. Thanks

[jturkey69]

im not very familiar with the ecotec's layout...but it could be an exhaust leak...on the exhaust manifold ...i have this problem now with my v6