gnuplot heatmap z-value data does not match color bar range

Question

I'm creating a heatmap from a file with columns x, y, z. I get a heatmap with what seems to be corrsct positions of peaks in the data, however, the peak values are about 1/10th the z-values in my data.

I have tried using set cbrange to change the colo bar range, but this only leads to plot in which the peaks get washed out.

Here are my data format, code, and output image respectively:

Data format (data has 200 X 200 elements):

   1.665      -0.031       0.355
   1.634      -0.031       0.395
   1.602      -0.031       0.434
   1.571      -0.031       0.471
   1.539      -0.031       0.505
   1.508      -0.031       0.533
   1.477      -0.031       0.555
   1.445      -0.031       0.568
   1.414      -0.031       0.571
   1.382      -0.031       0.563
   1.351      -0.031       0.546

Code:

set view map
set dgrid3 200,200,1
set xrange [-3.14:3.14]
set yrange [-3.14:3.14]
set termoption enhanced
set xlabel '{/Symbol f}_{i + 1}'
set ylabel '{/Symbol y}_{i}' off -3,0
set size square
set palette defined (0 0 0 0.5, 1 0 0 1, 2 0 0.5 1, 3 0 1 1, 4 0.5 1 0.5, 5 1 1 0, 6 1 0.5 0, 7 1 0 0, 8 0.5 0 0)
splot "plot-pmf-out4.dat" using 1:2:3 with pm3d
set terminal postscript eps enhanced
set output "pmf-plot4.eps"
replot

resulting image after calling gnuplot