Unless your grandparents have legal custody of you, no, they cannot consent to your emancipation.
Not all states will emancipate a minor. In the states that do, you need to be able to show that you are able to completely support yourself. That does not mean paying your car insurance, cell phone bill, buying your own clothes and the occasional meal; it means that you are also paying your own rent, utilities, all your food, transportation, health insurance, etc etc etc.
Notwithstanding all of that, if you are truly "almost 18" the likelihood is that you will BE eighteen before an emancipation petition could be heard.