You may need to adjust the response time, as it sounds like it's possible that this could be causing the problem, either that or is the mic close enough to your mouth to pick up your voice?
I had a similar problem (using my xbox360 controller for the game when using that in the game. It opened up the menu and by the time I was attempting to give a command it had either closed or I got the response from my race engineer "sorry, say again" etc.
Have you also "trained" your PC/Game to recognise your voice? You'll need to do this too, so it'll be able to distinguish your own voice pattern/accent and then work correctly for you in game. I did this in Windows and it took a little time and then also had to adjust the volume level for my headset mic to pick up my voice clearly. After I did this it worked fine for me.
There's a profile that you could possibly use here at this link.
Give that a go and see if it works for you.