Hi all,

First post here but been snooping around this forum for a little while until I finally had an issue myself. Now I understand this has been brought up one or two times and everyone points at the butterfly valves but mines seem to do it regardless if my performance valves are open or closed, when closed it is slightly quieter which I demonstrate in the attached video.

Car had its B service back in the end of Jan with a sparks and gearbox fluid change also but I've only noticed this issue last few days.

Everything runs fine, no engine lights or warning, performance is still perfect with no issues and my question is do I need to worry about this? Do I need to get it recitifed or just live with it?

The car only has 16k miles on the clock and it's a 2016 plate with pretty much every option, it's a coupe c 63 amg as the title so silly yes 😂

Any ideas would be appreciated 😁

Thank you all!!

Anyone? 😁

That sounds like unburnt fuel igniting in the exhaust and not a rattle. It's not unusual for unburnt fuel to enter the exhaust, but it may indicate that your air/fuel mixture is too rich. The exhaust can make all kinds of noises from the metal expanding/contracting based on the heat, to unburnt fuel burning up in the exhaust. It seems you have to be right up to the tailpipe to hear it or do you hear it just standing next to the car?

Thank you for the reply, that is what I thought initially but it does even on cold starts after a few mins once the revs drop to idle but not as much as after a run it is more noticeable when I drive for a little while and park up and standing on the rear you can hear the little pops, seems to come more from the left side more so than the right.

Well, the catalytic converters are very close to the engine so they heat up quickly (1-2 minutes to reach 'light-off' temperature, so they quickly start burning off unburnt fuel) and during cold start the air/fuel mixture is deliberately rich. Too much unburnt fuel in the exhaust, though, can overheat the catalytic converter. Might be worth getting your emissions systems tested to make sure everything is working as it should. Could be a failing oxygen sensor for example.

Well it had an MOT not long ago and everything emissions related was fine. In the other post a member also stuck up a video and it makes the exact same noises and the issue was the butterfly valves.

I would rather avoid a visit to the dealer if I can as I don't have any extended warranty and last thing I need is to replace a very expensive exhaust as the other post said there was no fix and his exhaust was full replaced.

I'm thinking if it's o2 sensor surely my engine light would be on?

Would it be bad if I just leave it and wait till the issue develops?

This sound is spark plugs, they need to be replaced. I had this on my 2016 as well and when i replaced the spark plugs it went away.
When was the last time you had them replaced?

I had all my spark plugs replaced already less than 2months ago, end of Jan 2021 from MB. Wasn't cheap aswel! Surely it can't be this could it? The only difference I've done is I've always filled up with shell Vpower 99 but my last refill was Esso supreme 99 and still have half a tank apart from that I'm not sure.

odd the only time i heard my car make that sounds the plugs fixed it. I'll ask a few friends and see if anyone else as ideas.
Sorry mine wasnt it :/

Thank you for the help! Much appreciated 😁

IF the issue is butterfly valves you can resolve it by disconnecting the valve and plugging in a AWE valve simulator that prevents ECL

Not sure if it the valves as the pops are still there even when valves are closed but the pops are less noticeable when closed than open