I have a 2002 Bone stock GT. The Only thing that is changed on it is the mufflers and there flowmasters. When I accelrate hard I get a rattling noise from my engine area and for the life of me i can't figure out what it is. I hope someone is able to help me out here. Its only under hard accelrating when the noise comes.

 

Explain the situation more. For sure is it rattling? Mabye pinging?

 

Need more info...are you sure its coming from your engine bay?

 

ratteling noise like marbles would lead me to belive you have nasty detonation, and thats bad.

You could have some carbon build which is causing the problem could be bad gas etc.. I would try some 93 to see if it stops if it does then its deffinatly detonation and you have some other problem.

 

i really cant explain what i am hearing it is like i need someone to drive around with me to hear... but it is really bugging me..

 

Ah so its a loose hardware kinda sound? that makes me feel alot better i thought you were having serious detonation i was gonna say **** man.

Can you open the hood and hear it? maybe rev the motor some and see if the noise happens again?

 

What happens is the resonace from his new flowmasters is rattling his catalytic converter shrouds and creating a nasty rattling. My car does the same thing, so we are going to fix it soon, either with a nice new catted X or somehow adjusting the cats' heat shields.
EDIT: TRUE BLUE FTW!

 

Run high octane gas. It worked for me.

 

thanks guys for the help i know i really didnt explain it very well..
Oh by the way Ghostalker i am a chick..

 

I have the same issue with my 04 GT. It sounds like the Cats for sure.

I had the same thing going on with a 95 Eclipse turbo I had when I was younger. I installed a straight pipe and the problem went away.

I suspect the same thing on the Stang....