Car people: what the hell is this thing?

I don’t know what this thing is. It’s the wet/oily cylindrical thing that reminds me of a fuel filter.

Google Photos

It connects to the air intake:

Google Photos

I am… not a car guy, generally, and this is the first thing I’ve run into that my Google-fu is failing on.

ETA: It appears you may have to click on the photo to see everything; it cuts a lot off for me after posting.

Looks kinda like a vacuum modulator.

Car make? model? year? engine type? manual or automatic?

PCV valve?

That brand K & N is aftermarket I think so it looks like the vehicle has been modified from factory. I vote for some sort of vacuum modulator. If it rattles when shaken then it might be PCV valve. If it is a PCV and doesn’t rattle then it is stuck.

If you haven’t already done so might google mod kits from K&N for your make and model and find a parts list.

Thanks for the suggestions!

It is a 2004 chevy trailblazer-. Bought it (extremely) used. It is definitely a K & N aftermarket air intake kit… Hopefully this gets me on the right track!

Was it ever owned in California? It could be some kind of filter or charcoal canister from a kit made to bring a vehicle not built for California in line with California code. I can’t remember when it was that all manufacturers just decided to make all cars California-ready.

OK. I looked at some diagrams of 2004 Trailblazers. I am now voting for fuel pressure regulator.

YES! Thank you!

If you want a new one, look around. I saw prices from about $16 - $66. You might try Amazon, because they may have more than one brand, and will have customer reviews.