I dont know why i doing this vs I dont know why i do this

Some examples from the web:

• I know why you're doing this, Ronald.
• I want to know why you're doing this.
• It'd help to know why I'm doing this.
• I know why coach is doing this.
• Hannah, I know why you're doing this.
• I don't know why we're doing this torture.
• I think I know why charles is doing this.
• I think I know why Peck is doing this.
• We don't actually know why she's doing this.
• I don't know why they're doing this.
• Nina, I know why you're doing this.
• I need to know why are you doing this.
• I know why you're doing this.
• I also know why you're doing this.
• I know why you're doing this.
• I don't know why Dennis is doing this.
• I know why Haley is doing this.
• I need to know why you are doing this.
• I know why coach is doing this.
• I don't know why we're doing this.

Some examples from the web:

• I don't know why we insist on pairing them.
• You know why? That's show business.
• Letting them know why this happened.
• David, do not know why...
• You know why he never showed.
• Your holiness knows why we are here.
• Now I know why I never married again.
• (Laughter) No one seems to know why.
• So I want to know why.
• Professor Norton. God knows why.
• Who knows why Mathew does anything.
• Publicly, everyone else knows why our heart aches...
• Sorry, I don't know why I did that.
• I waited till I saw the sun I don't know why I didn't come I left you by the house of fun I don't know why I didn't come I don't know why...
• I'd like to know why anyone should believe your client.
• I know why nobody wants to go after Teddy Bomber.
• You know why I'm asking...
• We didn't know why they made it so easy.
• So now I know why you tried to fight the Chair.
• Your people are dying and I know why.