HOT_SAUCE_and1

Just curious how does the crackle popping sound generate? Is it a "fake" sound?

Mike5215

It's a real sound. I believe it's caused by the spontaneous ignition of excess unburned fuel in the cylinders but don't quote me on that. So these C450s that have stopped crackling, was this after a service visit or did they stop on their own? Is the suspicion that the service techs are remapping the ECU under a directive from MB?

Sma2c

I do not know for sure, I think it is likely that it is fake given that we do not hear it in other modes and by the reports I have seen no exhaust valves. If it was just the sound and the car reacted normally I would just move on, not worth the hassle. The dealer just informed me that their "Quality control driver" is testing my car against a new one on the lot.

Sma2c

Hello Mike,
My car had only been in the shop once prior to replace a tire (pothole versus sidewall). Do not know if they did anything else, it was there a day waiting on a replacement tire.

Mike5215

The crackling stopped right after the service visit? A buddy of mine is an MB SA. I just texted him about it and asked if there were any TSBs (technical service bulletins) on the issue.

DapperStyle

With dealers they never check for updates on their own which to me seems rather stupid but time is money and any extra time spent is money lost to the service dept. I'm just saying I can't see them updating anything if he only brought it in to replace a tire.

When I first took my W204 to get Service A done I forgot to mention that I was having some bluetooth issues which at the time didn't bother me much. A few weeks later the issue got considerably worse so I called them and brought the car in, turns out there was a software update to fix that exact issue. But they didn't update the car when I went in for Service A or even bother to see if there were any updates. It was only after I mentioned the issue that they decided to apply the update to fix it.

Personally I feel that before you take delivery of a car part of the dealer prep should be applying all TSBs and software/transmission updates but I guess it's not realistic to expect that. When I get a new lease that will be part of my negotiation if they are willing to do it.

HOT_SAUCE_and1

The crackle is the reason why I drove in sport + and honestly I do think it's real because of the smell of burning fuel/oil

nvestr

The crackle is real. I recall MB stating that it is created by design through a "controlled misfire" of one or more cylinders...

flagman

Not really sure what you mean by "fake". It's not just a sound created by the audio system (as in a few other cars) - that would be fake. It is a real combustion sound that comes out of the tail pipes, apparently created by the engine management system controlling the fuel delivery and ignition. And as noted above, it is caused by the burning of a small amount of fuel in the hot exhaust system (not great for your gas mileage!). This program is active only in Sport+ mode. Mercedes describes it as follows in their literature:

Especially the "Sport Plus" programme delivers impressive hallmark AMG dynamics and enhances the emotional appeal: partial
cylinder suppression during gear changes by means of a momentary and precisely defined retardation of ignition and injection
under full throttle speeds up the gear changes, and can also be acoustically experienced by the driver. The emotional doubledeclutching
functions during downshifts and the "exhaust rumbling" in overrun mode provide the fitting accompaniment

flagman

+1

HOT_SAUCE_and1

I asked because some idiot was telling me it's fake? Lol I was like how fake can it be if the sound is coming from exhaust itself?

Vertice

Is the car up to operating temperature? It won't crackle until the temperature gauge in the instrument cluster is slightly past the middle.

Sma2c

The car is at full operating temp when attempting. I has been nearly 3 weeks since I noticed it and tried every which way.

Sma2c

Flagman,
Where did you copy that verbiage in red from? My dealer is very confused, I would like to send them a link to that page. Even after driving my car and a new one from the lot. Asking "So, is it the sound inside you are not hearing or the sound outside?" Uh yeah, no sound at all fellas. That and it hangs at high RPM...

z28lt1

The popping is mostly on the downshifting. Sounds like yours never gets to the higher gears, so you have less downshifting. Do you get the "proper" noises if you manually upshift to 7th and then manually downshift (or let the car do it).
I know the transmissions learn or adapt to driving, perhaps yours is holding gears based upon what is has learned? I think I saw a reset procedure somewhere on here, but I may be confusing it with my other car forums. Generally battery disconnect or a fuse or two pull.

EDIT: For previous MB cars, seems like this was a transmission reset (although a few posts say it is throttle only). Worth a try, not sure if it will actually do anything on the W205:

1) foot off the brake during the whole procedure
2) press the Keyless Go Start button once
3) press the accelerator to the floor and hold for 5 seconds
4) press the Keyless Go Start button twice to turn off the ignition
5) release the gas pedal
6) Wait at least two minutes before starting the car.

BeemerToBenz

Thanks, everyone, who commented on my experience with trying to order my c450 and the dealer shenanigans that ensued.

I took Mike's advice and called the dealer who had the car I wanted. They were very accommodating and after some work at the dealership, we did a deal and I drove away with my new c450 this evening. After a one hour drive I can already tell I will love it. I'll post pictures soon. Appreciate the comments and support here. Good community on this forum. Keep it up!

tmoneyC450amg

Congrats and enjoy the beast!

inhartwetrust

Fantastic man! Glad everything worked out for you, enjoy the new ride.

Sma2c

Thank you for the advice Z28lt1, I will try that this evening.
I pick up the car in a few hours.
After telling me the QC driver found what I was talking about they came back to me yesterday evening saying they had just heard from MB Germany (It was 1:00 AM in Germany...) telling me that my car is not "code 165" should have never made the exhaust burble. When I asked why it did prior they just said "maybe it was still breaking in, it never should have" I directed them to the MB press release that explains it. He assured me that a code 165 car would and it is an electronic module that plays through the car speakers and that the two C450 they have on the lot were not code 165 and did not make the over run burble sound.
Not buying any of this BS I told them I would not accept that response and asked who I should talk to next. He directed me to call MB USA directly.
I called them and they have started a case on the car. They also assured me that there is no "code 165" option for the C450. Interesting.

inhartwetrust

It's been tested and proven externally that the sound is not fed through the C450 car speakers. That dealership if you dealing with is full of ****, I would cut communication with them ASAP...no way you want to do a deal with someone like that.

Mike5215

I believe per Mercedes, Code 165 is "Vehicle servicing dealer ****ing clueless and prone to just making **** up to stop customer from complaining" if I'm reading the build sheet correctly.

So it's a special electronic module that plays a fake over-run sound through the speakers and the reason your car used to do it was because the special electronic module was just getting broken in? How the **** do you "break in" a module?

nvestr

Yes, because this sound is coming from the car's speakers...

z28lt1

We'll in fairness to the dealer and its BS, I interpreted it as it doesn't have the made up 165 module, and only made the sounds because the engine itself was breaking in, and now the engine is broken in, it's "properly" quite. Still a huge load of crap, but maybe a fraction of a percent less than the module itself breaking in.

I would have said Sma2c should take the service manager on a test drive of a new one on the lot, but that still allows them to use the same break-in excuse. Hopefully MBUSA or another dealer is more heplful

Mike5215

It's a video of a C450 being driven around an office park. What about it suggests the overrun crackle is coming from the car's audio system?

inhartwetrust

Send them these videos (and the one above) and asked them to explain how the in cabin speakers are driving the sound to the rear bumper mounted cameras. That should shut them up pretty quickly.