I have a 2003 Nissan maxima that has such an annoying empty spray paint can noise when it's in idle, it doesn't happen when I start up my car it only when it's been running for a bit in park, while I'm reversing or when it's in drive the noise isn't there but if I have it in neutral or in Park it's there and super loud. The sound seems like it's coming from somewhere by the intake manifold, I have a feeling it has something to do with the power valve actuator but I don't want to tear it apart if that's not the issue.

 

My guess is one of three things: loose heat shield, failing precat that is breaking up, or idler tension pulley. And the frequency of the very selective RPM is causing it to vibrate.

 

my idle tension pulley rattle, is only while driving around 1600rpm~2100rpm

 

I have a rattle when I'm accelerating as well I thought it was the knock sensor but I just replaced it and it's still happening, I also have the idle rattle that happens even when my RPM is teetering on 1 I just want to find out what it is so I can fix it. Im half tempted to just pull a motor from the junk yard at this point if I can't find the source