Speed Hack doesn't work anymore...

every time i try to use speed hack with cheat engine, after 30 sec the game stops and show black screen with red letters "Security Error"

Is it impossible to use them anymore? How do they detect the speed hack and could we bypass the detection somehow?

you'll have to view the anti-cheat script with net reflector and nop them with cheat engine. you're most likely banned by now in that game.