My car is making knocking sounds. No malfunction shows. Loud at times

I am having a similar problem describe it more like a tap, tap, tap... I see your post was a few month back, did you find the problem... Also, no missing in engine or rough running, smooth... My right side engine tap is in lower gears and does not tap all the time 50/50... No engine lights showing... Definitely notice not shifting as smoothly when tapping and just a little loss of power... When no tap humms, purrs and