Whenever I drive for over and hour my car has a tendency to knock when I hit a bump on the freeway. I switched to 92 octane and that helped for a while, but now it seems to do it more often, no matter what kind of gas. It only knocks once right after the bump, what the heck is goin on??
Thanks

 

Try checking your trans mount. They'll give you a good "thump" once it a while. Also, look for exhaust components that can bump against stuff- like where it goes over the rear axle.

A bump in the road can not cause detonation inside the engine.

 

At first I thought it wasn't detonation either, but sometimes it occurs without a bump. It seems to be triggered by bumps, but it also happens occasionally at slow speeds on smooth roads. Also, it never does it when the motor is cold, I figured it wasn't something hitting something else.