Mass analysis in a linear ion trap is traditionally performed using resonant ejection induced by auxiliary waveforms. For sinusoidally driven ion traps without resonant ejection, resolution and sensitivity are poor because mass-selected instability yields excitation along both the x and y axes simultaneously. Digital ion traps, on the other hand, have the advantage of duty cycle manipulation that can be used to change the ion excitation along the x and y axes. Consequently, the duty cycle can be used to enhance the resolution and sensitivity for mass-selected instability in a linear ion trap without the application of an auxiliary waveform. This work introduces and explores mass-selected instability in a linear trap without the use of auxiliary waveforms.