Got bored today and decided to tackle a rattle from the stock sub on my Dad's 06 MDX. The rattle was mainly heard from the outside, not the inside, but like I said I was bored. All I did was pop out the sub. There is actually a minimal amount of deadening material there already. theres a small 8x8 piece of vibration damping material on the panel directly behind the sub and 12x12 piece of 1.5 in thick blanket material. I took the padding out and put about 1 to 1.5 sq ft of edead on as much as I could reach in there. However that eliminated all the rattling inside, but nothing outside. Turns out, there is a flapper valve type thing in the bottom of that same void that the sub goes in and this is what was rattling. I believe this is to let fresh air circulate or something? Its like a black rectanglular port and I stuck my hand in it and there felt like a rubber flappy valve. Kinda like a one way air vent. Anyway, I stuff a bunch of polyfill in there to fill up the bottom of the cavity and surround the plastic valve box thing. No more rattles at all!

Anyone know if there are any consequences to plugging up that thing though?

 

Geez, ever since i got my system my whole trunk has a mean rattle

 

About the only thing I can think of is it may have been pressure vavle when closing the rear hatch...