S13 firewall noise. Help?

[Doritofu]

Kay so, I have a RHD S13 and recently i think something came loose in my firewall.
It's pretty confusing, but every time i close the door i hear a rattle like somethings dropping. I never hear it while driving. At first i thought it was in my dashboard but i went right underneath and now i think the noise is in the firewall.
I think it might have something to do with airflow inside the car because if i have both doors open, and i close one, the air goes out the open door. but if both doors are closed the air goes through to the firewall and makes this rattle noise.
This all sounds very complicated but i've tried to explain it the best i could, any help would be great.
Thanks.

[Gavwan]

Open your window then shut the door

[Doritofu]

lol
I have another problem with that, i cant wind the windows up when the doors closed or the glass stays outside the trim and water just comes straight in, also the reason i have to push the window in when i wash the car, lol. So many problems with this car but oh well, it's awesome on the whole.

[Gavwan]

The only rattles and knocks you need to worry about come from the engine or suspension area. Trust me if you actually drift it regularly, you'll get to know "ahh that's the rattle it always does" from "hang on, that's a new knocking sound better get it on a ramp"