I just started noticing a new noise on the 2007 HHR LS. I do not hear the noise when I am driving mildly. When I accellerate, or go up hill there is a noise kind of like a rattling lifter, or a exhaust, or a vacuum leak. when I ease off the throttle it goes away. My car had an oil change around 500 miles ago, and there is no noticable loss of power.
Any Ideas?

Thanks,
Matt

 

I'd be willing to bet that it is a heat shield on the exhaust. Sound kinda like a pop can with something rattling in it, but muffled?