Well just yesterday I got curious as to whether I could figure out how to remove the stock air filter box to access the air filter, and was able to successfully remove the box. I did not disconnect the piping or the MAF unit, just the box from the front port within the front body. Checked things out, stuck things back together as best I could. My intake is just stock, and it's an AT. Today when I tried driving the car up to 5000 RPMs with moderately hard acceleration, I notice that the intake note comes out as a sort of deeper sounding whoosh than it normally should be. It's definitely louder and deeper, but it also reminds me of something not being sealed tight. There isn't any noticeable decrease in acceleration as far as I can tell, just that deeper sound. The sound doesn't occur if I just apply very light pressure to the gas pedal, even if I rev it up to 5000...if the pedal travel could be split into 4 stages, I would say the sound comes in at the 2nd stage onward only. It's kind of funny in a way because it sounds like some aftermarket intake...except I'm worried that something's not sealing right.

When I look under the hood, at the front of the air filter box, I can see the foam ring that's in the front of the air filter box. Is that foam ring supposed to go deeper into the body area where the box connects to, to the point where I can't see it? I can't remember just how deep that foam goes into the body...but the box is pressed up as much as those big tabs that go into the rubber grommets would allow. I just hope I didn't really mess up something to the point where I'd have to take it to the dealer...

try pushing the box forward a bit. It fits in there snugly

Did you reconnect the vacum line going to the VFAD?

Do you mean the part of the air filter box that goes into the accordion-like thing in the back? I didn't touch that part when I pulled out the air filter box. I left everything connected, all I did was just lift the box enough from the front of the car to crack open the box and take out the filter.

Did you reconnect the vacum line going to the VFAD?

no VFAD on the auto

the filter might not have seated in all the way and the cover is not sealing properly. Remove the clips, lift the front and check if the filter is properly seated. Reinstall everything and try again.

Yep, I double checked the filter yesterday. It's seated properly. Still the same. I took it to redline yesterday and didn't notice any reductions in power, and the sound isn't as noticeable in 1st, but in 2nd, it REALLY starts making the deeper whoosh, and it's quite loud.

Did you fix the problem yet???

my guess is air is getting into the filter box AROUND the joint where the filter box meets the VFAD. its nothing to worry about, unless the noise bothers you.

just try pulling it all apart again and putting it back togehter.

I tried completely disconnecting the box so that I could pull the entire box out and reseat it into the accordion tube section. Did that, tightened up the retaining circle clip, also made sure the air filter was seated...still the same. I had a friend ride with me yesterday and he said the car definitely sounded different. I dunno what's wrong or what I did. There seems to be a slight lack of acceleration now when hitting the higher RPMs...for one thing, I know I didn't have to floor the gas pedal before to bring the RPMs up high quickly, I rarely had to go WOT for anything, but now it seems I have to floor it to get anywhere near redline, and the RPMs increase slower than before, especially in 2nd gear.

I've also noticed since this started that the car's cooling fans seem to turn on with every drive, and when exiting the car, I get hit with this burst of dissipating heat from under the car that never happened before. Could whatever is causing this extra noise be causing the car to overheat too because of something not drawing in air correctly?

Ok, saw this pic, and I noticed something...


http://img.netcarshow.com/ncs/Mazda/2004-RX8/m/0b.jpg


The front of the air filter box seems to be actually seated deeply into the tube in front of the box. Yet right now, my air filter box doesn't seat into anything at all in the front. I can plainly see this foam like ring that probably is meant to seal against something. There's a gap between it, and I suspect, that tube. Maybe this is where the problem lies? But as it is, I can't push the box any further forward, because it's already stopped by the grommets holding the box in place.

Ok. looks like the tube may have come loose from the carframe and the intake box opening when you tried to put everything in place. You can try to remove the black plastic piece surrounding the hood latch mechanism in order to access the tube underneath. It is held in place by 6 pop-out plastic grommets. Remove these and just pull out the blask plastic panel and try to reseat the tube.

If this does not work or you are not too willing to do this procedure then just take it to the dealer. Don't volunteer any information about how this happened. Just tell them the car just started making unusual noise and they should take it from there. You may tell them where you "think" the noise is coming from to point them in the right direction.

Ok. looks like the tube may have come loose from the carframe and the intake box opening when you tried to put everything in place. You can try to remove the black plastic piece surrounding the hood latch mechanism in order to access the tube underneath. It is held in place by 6 pop-out plastic grommets. Remove these and just pull out the blask plastic panel and try to reseat the tube.

If this does not work or you are not too willing to do this procedure then just take it to the dealer. Don't volunteer any information about how this happened. Just tell them the car just started making unusual noise and they should take it from there. You may tell them where you "think" the noise is coming from to point them in the right direction.

Thanks for the info on where I could look next...I'll definitely try popping out the plastic surrounding the hood latch and see what's going on there. No big deal for me as I've done it before to mod my parking lights with hyperwhite bulbs. And as far as the dealership goes...unfortunately I read about a mod somebody else did where they sawed off the little plastic hook that was sticking out right above the air filter box's front, which makes lifting the box out much easier. And so I went ahead and sawed off that hook myself...so it's pretty noticeable that the air filter box and whatnot has been tampered with. :( Most likely they'd charge me at least an hour's labor to look into it.

WHOO HOO! Thanks a ton wedge357 for that tip. That indeed solved the problem. The intake tube was pushed back into the car frame...there's a big foam ring near the opening of the tube as well that I think is supposed to be wedged into the car frame to hold the tube in place. That foam was completely popped out. Pushed the tube back in as much as possible, wedged the foam into the car frame opening, and then the air filter box front opening was able to completely seat inside the tube. Took a test drive, and the noise is GONE! Kind of miss it though because it did sound a lot more aggressive. But I'm glad things are back to normal.

Glad to help! :D