My break petal goes to the floor when I start it

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. I expect what you are experiencing when the vehicle is off is a harder brake pedal due to the power brake vacuum booster not lending assist to the pedal. If your pedal is going to the floor, do not drive the vehicle. You must have this checked professionally before you try to drive. If the pedal goes to the floor it is evidence that there is a leak in the system somewhere, either externally where fluid is coming out, or internally at the master cylinder where it mounts to the brake booster. A physical inspection is needed. This vehicle is not safe to drive. Seek guidance at a shop near you right away. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.