i just changed the front pads yestersday. now today while im driving im hearing a knocking sound whenever i coast but it goes away when i push the brakes or push the accelerator it goes . could anyone help me out on what it might be?

 

The clip on the pads may not be seated right. This seems to be common. You have to take the wheels off & double check them.

 

could it be that the rotor may be warped?

 

No. It sounds like your pads are moving. Make sure the metal retention clips are all in place and that the pads are in place. Also double check that you have the caliper bolts tight.

 

now it does it all the time even when i brake and accelerate.