The Low Energy Ion Ring (LEIR) at CERN is the first synchrotron in the Large Hadron Collider ions injector chain. The performance of LEIR is mainly determined by the number of charges extracted from the machine and transferred to the downstream chain of accelerators. Ions are delivered by the linear accelerator Linac 3. In the intensity accumulation phase, the machine operates with coasting beams: each injected beam is cooled, reducing its transverse dimensions and momentum spread, and brought into a stacking momentum position to allow subsequent injections. In this context, the evolution of the beam parameters for an injected beam under the effects of electron cooling, impedance, intrabeam scattering (IBS), and space charge is of interest in order to optimize the machine working point with respect to the accumulated intensity and to contribute to the understanding of the interplay of the different collective effects. This work describes the advancement in modeling coasting beam dynamics for LEIR accounting for the interplay of electron cooling, impedance, IBS, and space charge. Each effect is presented and progressively included to compute the simulated equilibrium longitudinal Schottky spectrum, which is found in good agreement with the measured one.