I was cleaning the throttle body today and a hose came disconnected. It's connected to a large black cyclinder mounted to the firewall to the left of the ABS, underneath the black air intake hose connected air filter to throttle body.

Does it loop around and connect back onto itself at that T connector? If so it's very lose. What does it do? If no one knows what I'm talking about I can post pics (apologies if I didn't describe very well.)

Nope, it makes no sense at all. What car/model, can you post a pic?

If it's a small hose, about 8mm, it sounds like the purge line for the charcoal canister (the large black cylinder). What colour is the marking on the hose?

doesnt seem to have a marking. It's from a TH solara. Heres pic;
http://img36.imageshack.us/img36/7462/hosex.jpg (http://img36.imageshack.us/i/hosex.jpg/)

Ok. I've just had a look at my brother's KE, and that hose just hangs loosely in the engine bay.

yeah just put it facing down so if it overflows it just will drip onto the road.