All the King's Horses - S2-E10
Audio problem: When McGarrett and Danno pull away from the curb in McGarrett's big black Mercury, the tire-squealing sound effect begins before the car actually starts to move. (Doesn't happen unless you're flooring it and "peeling out," which they're not.) (00:41:50)
Answer: He was fired. He never really appreciated his character. He felt Kono was portrayed as a big dumb Hawaiian and that the stereotype was racist. He also felt underutilized. He was fired after a heated argument with the show's publicist regarding his character. It seems there's not much details given regarding the incident or the firing, so it's seems possible he upset the show's producers as well.
Bishop73
No he said something derogatory about one of the Jewish producers that's why he was fired.