I had this issue when I did my knock sensors too....
If I'm not mistaken, one of the hoses sucks, and the other one blows (in a different context, that actually means the same thing....

)
If you get a CEL that says something is wrong with the MAP solenoid or something like that, chances are you've got them backwards, like I did. here's a close up view of them... oriented to the right is the front of the car of course. Good thing is, they're not difficult to get to, even with everything assembled except for the plastic engine cover.
