usaf1965

On my 03 GT convertable it makes a rattling noise coming from the bottom of the car everytime I accelerate.
Tap the gas, it starts rattling till I let off of the gas pedal. ANYHELP?

Z28KLR

"Bottom of the car" is a pretty big area, care to narrow it down a little? Does the rattling sound seem like it's coming from the transmission, exhaust, front or rear of the car?

usaf1965

It sounds like it is coming from underneath the drivers seat

Z28KLR

Check exhaust on that side. Figuring you still have a factory midpipe, see if the source of noise might be the rear catalytic convertor.

x_doug_x

Do you run 93 octane ? If not it might be spark knock, my 95 5.0 was bad about this when I bumped timing up. Only did it on acceleration. Sounded like an exhaust rattle.

usaf1965

I run 89

x_doug_x

Do you know if car has a tune on it from you or a previous owner? Have a tuner?

usaf1965

Theres no tune on it . Its stock

x_doug_x

There really isn't enough information here to pinpoint, is it only under heavy acceleration ? Could be loose exhaust like posted here, Rod knock, spark knock , cat converters falling apart, loose driveshaft bolts, bad u joints, the list goes on.

x_doug_x

If it does it just idling and it's loud, i'd vote on rod knock.