This issue will open the clubface and cause a slice. This is actually a preferred grip for finesse shots around the green to add loft and cause the club to slide on the turf. When used for power shots, this grip will cause chunked shots as well as the slice, and contribute greatly to a loss of distance.
Faults
A Weak Trail Hand Grip
Did you know?
The leading cause of the slice is a Weak Lead or Trail Hand Grip, and the Slice is exacerbated when using lower lofted clubs such as your driver.