avery.whss

When I accelerate at low RPMs/1st gear I'm hearing this kind of rattling sound ..sounds like its coming from the exhaust ..it's not there after the car hits 2500+ RPM (the sound is hard to explain but sounds like two tin cans kinda hitting each other but quite-ish) + The rotten Egg smell is back...I did put 91 in the car with about a half tank of 94 in it...Could the gas be the problem or did I blow something else up?

m a x i m u s

maybe the cats?

avery.whss

Not to sure....It was happening often after I put the 91 in it...but I just took it out for about an hour and kinda beat the crap outta the car in paddle shift mode (Never used them but holy s**t it gets bent in 3rd) and now it doesn't seem to make the same sound as much...No idea...I'll take it to MB and get them to check it out next week, and the smell isn't there anymore of rotten eggs..smells like a normal exhaust...if it is the cats should I just get stock ones or ?

Thanks guys

m a x i m u s

maybe something was stuck somewhere and you shook it loose. I used to play with the paddles in c and s mode and wasn't impressed until I found m mode. lol. what an effing difference. and yes, I've been flamed for "not reading the owners manual".

JimmyR

Could the rattle be "pinging" ie pre-ignition from the low octane ? low quality fuel?? I would see if it goes away with high octane fuel

avery.whss

could be...I usually run 94 (the highest in my city) and i put 91 in it thinking it'd be fine and I guess not? Lol...I guess these cars are picky eaters? It's kind of a pinging sound..I think you know what I mean.

m a x i m u s

good point, I missed the 94 oct part of your post, and we only have 91 here in the states. I agree that it's probably pinging. try the 94.

fly2nite

91 is California and Oklahoma that I know of, plus others I'm sure. In Texas, we have 93 and 94 at one station in Dallas. They also have a few stations around Texas that sell 100 at the pump if i remember correctly.

2012C63AMG

I think every benz I have owned at around 40k miles I have had the cats crack, you usually get a rattle then you will get a smell of exhaust down the road, smells like you have that smell now should be a simple thing for the dealer to check out. Warranty on emission devices is very long on cars over 4 years+ I want to say 7 years but thats off the top of my head unless they change things.

Does the sound change or possibly go away when the car heats up? The leak might be closing as the cats heat up and expand.

I did have an issue with my older C63 from 10, it had a intermittent rattle at only a certain RPM, turned out to be related to the brake lines not being properly installed or something like that, freaked me out to hear that.

avery.whss

Did it at very low RPM in low gear, Pretty sure it was the 91 gas from shell....I ran all the 91 out and Filled it back up with 94 from chevron and no noise..Runs normal again...my friend who knows cars a bit told me due to the high compression in these cars certain gas can make it "ping"

2012C63AMG

Must of been one hell of a ping then. I have accidentally put 87 in my car and it ran fine I couldn't even tell much just a tad lower on power and I even have a tune, and that was 10% ethanol in that also. We only have max 91 in my current state and that also has 10% ethanol.

m a x i m u s

my car pings most of the time with 91 pump gas.

JumpinJim

m a x i m u s

I wish i could tell my car that. lol.