jasonwang992

Hi guys. Recently just discovered a weird noise with my 2022 C2S. It happens during a very specific situation: gradually decelerating from higher gears into 2nd gear, while the car is sitting in 2nd gear and around 20-25 kph (12-16 mph). Eight out of ten times, I can hear a weird clunk noise coming from the back of the car. It's always 5 or 6 clunks which sound like two pieces of metal slapping each other. It doesn't matter whether its on Normal or Sport, or whether the exhaust valve is on or not.I cannot determine whether the sound is coming from the exhaust, the gearbox, or the engine, since every single one of them is located at the back of the car lol. The car has 10k kms (6000 miles) on odometer, and an aftermarket exhaust system (which was double checked for correct and tight installation after the weird sound popped up). Should I concern this problem a lot and have a thorough check?

vanlieremead

You didn’t mention if you have a PDK. Those will sometimes clunk and a visit to the dealer for cal clear might do it. If a PDK, switch to manual and do a downshift at those speeds. Mine sometimes cluck too but I typically don’t run in manual.

jasonwang992

Yes mine it's a PDK. Just contacted dealer for an inspection. Hope it woulnd't be something serious

jasonwang992

Just went to the dealer, and they provided a new version of DME software for the exhaust system. After flashing the new software I can no longer hear the clunk noise, but the pop and bang sound became siginificantly quieter which I'm really disappointed. Dunno what's actually going on here