I have a 2005 Pontiac grand Prix GT that just started making a loud noise like a motorcycle while accelerating.Do anyone know what that can be?
The only thing I can tell you is try removing the serpentine belt then start the engine and listen, if the noise is gone then you know it is one of the accessorie drives, ie and idler, alternator, water pump, A/C clutch, etc. If the noise is still there with the belt off then it is engine internals. Don't run the engine too long with the belt off, as it turns the water pump.
Not trying to be a smart butt... Do you have a hole in the exhaust somewhere? Not completely sure what you mean by "loud like a motorcycle"
I agree, the info given is pretty vague, but a plugged catalytic converter comes to mind.
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