car amp and subs

Hey i have a 91 celica that i had pro. ist. a couple of months ago and now when i drive if the car jerks at all. I get a puching in my subbox for some reason the subs sound great other than that i contacted the company that installed it and they have no idea. Just wondering if any one know what could be causing it and how i can stop it? thanx

check the ground off of your amp, if it is loose, it could be shifting when the car jerks, and that would cause your punch

Evan

I think I had the same trouble one time. It might be your RCA cables if it isn't your ground. Just make sure they are in there correctly and that they are working fine. I think that is how I fixed it???