frescagod

2010 6MT, 49,000 miles on the odometer. I took the car in for a notchy gearbox, and they said that the tensioner was making noise so they replaced it under warranty.

Driving it home tonight, I noticed that at wide open throttle, the engine sounds probably ten times louder than it did before. It's hard to explain, but I hear a deeper, throatier sound coming from in front of me, and I can actually feel it more through the steering wheel. At 10-75% throttle, it does not make this noise, but if I floor it, it's noticeably louder. Before, the sound was pretty "isolated" to the engine bay and didn't permeate throughout the cabin, but now it is excessively loud.

Nothing else seems different...idling is still around 750 RPM, and there doesn't seem to be a loss of power.

Would their work have had anything to do with this at all? I checked the trip and they only drove the car about 2 miles. I'm 99% sure this sound isn't my imagination.

Any thoughts or help are much appreciated.

BaoZZeR

Take it back to the dealer. Your idle speed is low but IDK if its suppose to because I think mine is usually above 1000 but than again I don't think that's normal.

frescagod

fixed myself. they checked the engine air filter and left the box/cover open without the clips locking it down. locked down = no more weird low grumbling sound at WOT.