hiiiiiiii!!!!!!!
ofcoarse u can clear iit without any coaching.
infact i think if one prepares by self,there's better chance of clearing iit.
all u have to take care of is that stay focused and do not get diverted.
try to solve ques by urself.
try to apply ur own concepts and create ur own methods.
keep up the hard work going and u'll surely clear jee with a gr8 rank.
all the best!!!!1