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Discussion Starter · #1 ·
Hi guys I have a 2013 f31 msport automatic. In 1st, 2nd and 3rd gear I have a knocking sound coming from under the car, also when I accelerate hard the knocking sound is there. Any one experience this before if so any suggestions on what it could be. Thanks
 

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How fast is the knocking. Does it change in speed or loudness as you press on the gas.

Could be a loose exhaust system bracket allowing it to bang against the under -body as the engine shifts position.
 

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Discussion Starter · #4 ·
How fast is the knocking. Does it change in speed or loudness as you press on the gas.

Could be a loose exhaust system bracket allowing it to bang against the under -body as the engine shifts position.
Hi, It doesn't change or get any louder. Just after the car changes gear in 1st 2nd and 3rd it knocks about 3 times and then when I accelerate hard it knocks 3 times
 

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I had that and it turned out to be the parking brake cable was loose. Shop fixed it in ten minutes.
I got charged $800 for that repair. They said they had to take the fuel tank off and a heat shield. It was a $50 bracket that broke. Yours must have just been loose.
 
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