Coffee enemas are for cleansing the liver and should not be used for relieving constipation or cleansing the bowels. After coffee enemas it is natural to have less urge for defecating since the rectum is emptied out.
To make the coffee enema more effective you need to have a fairly empty descending colon, you can have this by either taking cleansing enemas or by laxatives.
For more detailed info please read my blog, titled "My challenge" link below.