Quote Originally Posted by boondocksaint View Post
Can someone describe the rod knock sound for me? I have a sound that reminds me of an exhaust leak, but I can only hear it INSIDE the cabin. The motor makes no such noise with the hood up. Also, the motor noise is very loud (like the sound of air blasting out of it) when at throttle. This is another thing that makes me believe there is an exhaust leak.
Might be that your EGR nut has come loose. The EGR valve is between the intake manifold and the firewall, and the nut threads UP into the bottom of the valve. There have even been cases where it's come all the way out of it's threads and has been found just spinning at the bottom of the EGR tube.

(Similarities from another thread) http://www.vehicross.info/forums/sho...hlight=egr+nut

Mine did the same thing a couple of years ago, resulting in a "dieseling" sound during acceleration. If that's the case, a simple re-tightening of the nut with a 22mm wrench should do the trick. At the time, I also applied some anti-sieze to the threads before tightening, and while I can't say for sure that the anti-sieze helped it stay tight, I do know that it hasn't happened again.