Ok, although I'm a newby, I'm going to answer this one. I bought a 2006 Mazda6 3.0L and that's one of the first things that I noticed. I would notice it most in parking lots under a tad of accelerating. You hear this ticking sound, if I recal, it speeds up with the RPM but then you stop hearing it because the engine gets louder. It took me while to get to the dealer and complain about this. The first dealer thought it was inside the engine and it turned into a big mess. In the end THEY WERE WRONG. A few months later, that ticking sounds was annoying again so i took it into another dealer and they knew right away what it was. THE PURGE VALVE. The said something about a hose that needs to be replaced, easy to do and it would cost about $120. I was a bit skeptical but I said OK and do the work. To my surprise the were RIGHT!! The ticking sounds went away! I was so happy. But....... after about 10 months, it came back. So I think it was a temporary solution but atleast I know what causes it now 