Mike in Atlanta

I have had a tinny vibration from under the car for quite some time at certain RPMs. I am almost certain it is the thin piece of metal suspended over the catalytic converter, which I assume to be a heat shield (when I jack up a side and reach underneath, when tappped, that piece makes a similar sound as the vibration that I hear while driving). What I can not determine is how it is fastened to the chassis in order to tighten and/or dampen. It doesn't seem to be in any danger of falling off; just causes a vibration that bugs me to no end. Can anyone offer suggestions? Thanks.

RedY2KS2k

Does it make the noise at a certain rpm both when accelerating and when decelerating? Or does it make the noise only when decelerating from about 4k to 3k rpm?

9KADDCT

your heat shield may be loose

CKit

Sometimes the honeycomb inside the catalytic converter breaks off and rattles as well.

You can buy a piece of Dynamat to put on the top of the heat shield to keep it from rattling.

Mike in Atlanta

It is a tinny vibration sound (such as a thin piece of metal like the heat shield would make) that happens not necessarily 100% of the time, but anywhere from idling to acceleration to deceleration and even cruising. So, there is not specific RPM at which this vibration takes place. It is most notable during a shift (when motor quiets for a brief moment), or when travelling alongside a median wall where the sound from under the car echoes back to me. It probably vibrates more often than I notice, but is drowned out by the sound of the motor.

I doubt that it is the cat itself. In my experience, a busted up cat has a heavier rattle sound, and you can hear it rattle inside the cat when you tap it from the outside of the cat; I am not experiencing this. I am almost certain that it is the heat shield, but I just haven't been able to locate any loose/missing bolts.

Does anyone know how many total attachment points there are for the heat shield? Are there any welds, or is it all hardware? I have limited vision utilizing a floor jack in the garage (can't get far enough under to see entire heat shield). I may try using a mirror today. Would dynamat be able to withstand the extreme heat that the heat shield is subject to? I would think it would melt/burn.

Mike in Atlanta

OK....so on further inspection, I was wrong. Getting under the car while it was running, I sourced my noise to the resonation chamber on my Spugen exhaust. I called Spugen, and they said that it is only welded to the pipe on one end, and that a couple of spot welds on the other side should quiet my problem. I'll keep you posted.

Update: The resonator was loose against the pipe entering it from the front. (only the rear portion is welded to the pipe). At Spugen's direction, I had my friend weld the resonator to the pipe on the forward section, and voila!.....no more rattle.