Hello, Unless my book is wrong, for 2004, Acura I show models, 3.5RL, NSX, RSX, TL, and TSX. I don't show an EL model. The only models with 4 cyl are the RSX and TSX. The information I am giving you is for the RSX. Hope this helps.
For the Engine Air filter
1. Remove the clamp (A) and the screws (B), then open the air cleaner housing cover (C).
2. Remove the air cleaner (D) from the air cleaner housing (E).
3. Install the parts in the reverse order of removal.
Cabin Air Filter
Dust and Pollen Filter Replacement
The dust and pollen filters should be replaced every 30,000 miles (48,000 km ) or 24 months whichever comes first. Replace the filters more often if the air flow is less than usual.
1. Open the glove box. Remove the glove box stop on each side, then hang the glove box down.
2. Remove the filter lid (A) from the blower unit, then pull out the first dust and pollen filter (B). Slide the second filter to the left, and pull it out.
3. Remove the filter (A) from the housing (B), and replace the filter.
4. Install the filters in the reverse order of removal.