Just poured seafoam into my car and have negative result?

the hose that you have off in the picture is the breather hose, the other end of the pcv valve system. an easy way to find a good source of vacuum on that thing would be to find the hose that goes from the vacuum brake booster up to the intake manifold. that one will work well for your purpose as long as you have a smaller hose that will still seal inside of that one. i have to ask what you are trying to accomplish here with the variety of things that you can use sea foam on. i have used it to clean the engine, intake and fuel system on my car and i had nothing but good results with it.