How do I (further) lower the pH of a pyrrolidine solution? Pyrrolidine ($2~\mathrm{mol}$) is slowly added to $164~\mathrm{ml}$ conc. $\ce{HCl}$ in $200~\mathrm{g}$ ice water to adjust the $\ce{pH}$ to $3-4$. When it is mixed, the $\ce{pH}$ is $14$, how do I lower the $\ce{pH}$ to $3-4$? I cannot add more $\ce{HCl}$ because it only calls for $164~\mathrm{ml}$.
A pH of ~ 4 would correspond to a solution of pyrrolidinium chloride.  Use less pyrrolidine or more hydrochloric acid to arrive at that point.

The commercial concentrated hydrochloric acid is 37 % (w/w), this would be a concentration of ~ 12 M, and 164 ml of that is slightly less than 2 mol HCl.  It's very strange that you are seeing a basic pH.