  CMB photons travel from the last scattering surface, when the primary CMB has
been generated, along the surface of the light cone to us. During their travel,
they are affected by many secondary effects such as the integrated Sachs-Wolfe
effect and CMB lensing. These CMB secondary effects modify the CMB primary
power spectrum adding degeneracies and decreasing the sensibility to primordial
parameters. The possibility to reconstruct the primary CMB anisotropies will
allow us to have a more direct observable to test the physics of the early
universe. We propose to study the imprint of features in the primordial power
spectrum with the primary CMB after the subtraction of the reconstructed ISW
signal from the observed CMB temperature angular power spectrum. We consider
the application to features models able to fit two of the large scales
anomalies observed in the CMB temperature angular power spectrum: the deficit
of power at $\ell \sim 2$ and at $\ell \sim 22$. This method allows to improve
significantly the constraints on the features parameters up to $16\%$ for
models predicting a suppression of power of the quadrupole and up to $27\%$ for
models with features at $\ell \sim 22$, assuming instrumental sensitivity
similar to the $Planck$ satellite (depending on the goodness of the ISW
reconstruction). Furthermore, it gives the opportunity to understand if these
anomalies are attributed to early- or late-time physics.
