If i get feces on a little scab, not big and healing, and i washed it with soap and water and alcohol can it still get infected?

If your feces is clean, than no problem. If wound is closed, than no transmission. An open wound and infected feces can cause a Septicemia or a Sepsis. Washing is the correct response, look for any adverse effects, and see your PCP if any occur.

That is the typical mechanism through which many skin lesions become infected, however you did all you could to prevent it. Watch the wound until fully healed.