smelly stuff in cabin

I have a 2005 civic dx.

there is a smell coming into the cabin through the vent. it smells like exhaust, oil dripping and burning off, fuel, some mysterious object burning, or anything else your imagination can think of. it only happens when the car is warmed up, vent is set on 'fresh air', and is idling at a stand still.

have brought it to many different garages and people and they all say they can't figure it out and its fine. i think they just don't want to deal with it, cuz it will take a long time and theres no money in it. its lame but i don't blame them.

but they all came to a similar conclusion:
no exhaust leak, no oil dripping, no trash caught underneath the car and burning, no dead animals, no mold, and the car runs fine.

i do have a hunch, what about the gasket in the exhaust manifold? i have read that it can form cracks but won't neccessarily cause a loud noise.
could some exhaust leak out and waft up into the cabin through the vent?

based on this info, does anyone have any suggestions?

one more clue, this car was rear ended and pushed into the car in front. the rear and front ends were repaired cosmetically, rear and front bumper assembly were repaired and the radiator was replaced.

thanks for your time!

I read on another forum that the cause of the funky oder can come from a dirty cabin air filter. Have you checked that? I'd give all your air filters a look over to make sure they are clean.

I have an 01 civic ex and havent had this problem in the last 2 years I've owned it.

The smell is likely coming from a very,very, very, dirty cabin air filter.

The cabin air filter is located behind the glovebox, and can be easily changed in about 15 minutes.

For you vehicle, the cabin air runs about $15.00 from most retail auto parts stores (Advance Auto stocks these, that's where I get mine from).

Keep in mind that you should change your cabin air filter at least once a year (twice a year if you live in area where dust, dirt, or pollen is thick). Once you get this changed the smell should go away on its own. However, if the smell continues even after replacing the cabin air filter. Hit you local dealer up for something called a "A/C duct fogging cleaning". This is a tool that emits a "fog" or "smoke" that goes though you vents and cleans out any mold, smells, or gunk. It's expensive though, usally runs about $150 or more.

Hope that helps.

that is the RAT that you forget to take out

Yeah this should solve it :) I replaced both of mine and now I have clean air

make sure you put your hand in and get all the junk out of the blower