We have computed cross sections and asymmetry parameters for the C 1s photoionization of CX4 (X=H, F, Cl) using the Schwinger variational method with Pade corrections. We present a comparative study that shows the influence of the identity of the X atom on the computed cross sections. Predicted cross sections are in good agreement with available photoionization and photoabsorption experimental data. We conclude that the presence of heavy outer atoms produces resonance structures in the photoionization cross sections and in the asymmetry parameters. We find a single nonvalence resonant state in the photoionization of CF4 and multiple resonances in CCl4 that have significant d-orbital character in the vicinity of the Cl atoms.683