State-selected delayed pulsed-field threshold photoionization spectra of HCl and DCl are recorded in double-resonant transitions through the F (1) Delta, E (1) Sigma(+), and g (3) Sigma(-) states of the 4p pi Rydberg configuration. Comparison of observed rotational line strengths with calculated spectra, as well as with available time-of-flight photoelectron spectra, provides useful insight on the influence of spin-orbit and rotational autoionization on delayed pulsed-field threshold photoionization of HCl. Spin-orbit and rotational autoionization are seen to dramatically reduce the ion rotational intensity associated with the upper spin-orbit level of the ion.