throttle

[K321]

Hi. i have just done 800 miles in my 15 yr old saab across europe.it didnt break down once. however i noticed from the start that when i touch the throttle. i can hear this whirling noise coming from the engine. the harder i touch the throttle. the whirling noise goes faster, i also had the check engine light come and stay on, but amazinlg the car just kept on going, any ideas what it could be?