When I rev the car to about 3500 to 4500 rpms the car makes a noise almost sounds like lifters knoking but it isnt in the motor it directly under the car. I cant figure it out any idea's???

 

heat shield rattle maybe?

 

Mine was intermittent.

 

check your oil. it happened to me and it was a knock in the crank case. fill it up with oil and it will go away.

 

Hell I have that same problem now! Now my car viberates at about 3500rpms. I took it to the honda dealership here in KY. They couldn't find the problem so now I have to go to Frickin Florida to figure this one out!

 

If you have a test pipe, the 02 sensor may be loose. I know I had a problem with it for a while

 

Could be your catalytic converter too, was what my noise was.