How can I sponsor a minor 17 year old son who is in the US already?

Your son needs to receive a permanent residence status, and if by then he is under 18, you can file for his US passport. However, it is best if you consult with an attorney who would get familiar with all facts of the case.

The first place to start is to be clear about what immigration-related goal you are seeking and what eligibilities, options and strategies are most appropriate to consider. For example, if you are a U.S. citizen, then it may be possible that your son already is a U.S. citizen by virtue of your citizenship and operation of law, that there is no need to go through an adjustment of status process for your son at all; and that instead you might want to help your son apply for a Certificate of Citizenship as documentary evidence of his citizenship. There really is no substitute for working with an immigration attorney who, after learning all of the relevant facts, would be able to advise you and your son about attaining your goals. Some immigration law firms, including mine, offer legal services on a "flat fee" basis so that a client will know the total expense from the very beginning, and a few immigration law firms, including mine, offer an initial consultation free of charge.