Banging noise whe accelerating from a dead stop

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I have a 98 Audi A6. Immediately when I hit the accelerator from a dead stop I hear a slight bang that seems to come from under the car in the area under the front drivers seat. It only happens when I hit the gas and the car starts forward. I’m not putting the pedal to the floor either, just a nice gradually start from a dead stop. This is the only time that I hear this noise, nothing while driving or making turns. The noise sounds like when you might squeeze and empty tin box! that distinct bang you hear. What might this be?

Broken motor mount? Failing CV joint?

"Broken motor mount? Failing CV joint? "

+1

Are those costly to fix?

It depends on what you mean by costly. But generally no. They’re in the $2-400 range - except its an Audi, so who knows.

Of course, these are also WAGs - so it could be something else entirely.

I’m sorry but what does WAGS Mean? I appreciate your responses.

WAG means Wild A&& Guess. In this case, they’re educated WAGs. And ones I agree with.

However, once someone takes a look-see they may find it’s only a loose heat shield, or perhaps a tired sway bar bushing, who knows.

You don’t have an empty pop can under the seat, do ya?

Another possibility could be a bad center carrier on the rear driveshaft. I’m pretty sure this model uses a 2 piece shaft and a bad carrier could cause a thump underneath the seat. It should be easy enough to check and I hope that helps.