Poor cleaning is usually water not reaching the dishes rather than a weak detergent. Spray arms, the filter and loading account for nearly all of it.
Common dishwasher problems
All dishwasher guides
Dishwasher Leaving Dishes Dirty or Gritty
Dishwasher Standing in Water at the End of a Cycle
The filter, the drain hose and the disposal connection explain nearly every dishwasher that will not empty, including one easily missed installation mistake.