Crackling Noise!

[maximussp]

Hey guys,

I have a gs400 98. I just found out that when i put my car in reserve and steph on the accelerater hard, the car backs up and makes a loud metal crackling noise. The car still goes back but vibrates. I make sure its in gear and etc. BUt if i lightely step on the gas its fine, but when i step on it harder to accelerate, it makes a loud crackling sounds. I feel like its shock related, but i have no idea. Any idea what it could be guys?

-Kenji