3d plot goes across limits python

1`# trim the data
2y = np.ones(PDF_x.shape)*PDF_x
3y[y>95]= np.nan
4y[y<75]= np.nan
5
6
7# plot the data
8fig = plt.figure()
9ax = fig.gca(projection='3d')
10for i in range(PDF_capacity.shape[1]):
11    ax.plot(life[i]*np.ones((PDF_x.shape)),y,PDF_capacity[:,i], label='parametric curve')
12
13# set the axis limits
14ax.set_ylim(75,95)
15
16# add axis labels
17ax.set_xlabel('charge cycles to failure point of 75% capacity')
18ax.set_ylabel('capacity at 100 charge cycles')
19ax.set_zlabel('probability')`