JoshBlond

Just bought my C63 with 50k miles. drove it all the way from Corpus Christi TX to Kansas City. Ran like a striped ape. Something that i don't think is normal is the idle. Its different all the time. I think its vacuum related because i don't see any power loss. I haven't gotten any CEL's so I'm not sure where to start. Car is out of warranty so im trying to avoid the dealer. The idle seems to get even more aggressive whenever you get on the car. I took the car to the lake over the weekend and had to put 91 octane into the car and also on the way back from texas. Could a couple of tanks of lower octane gas cause this issue? Besides the idle this car has been an absolute blast. Thanks in advance for any input.

***also if anyone knows the reason behind my front passenger window not staying all the way up..? Very weird. I will roll the window up and it will lower itself about an inch...

INS1GNIA

Always nice to see another person from KC! Also congrats on the new purchase . I was reading some https://mbworld.org/forums/c63-amg-w...vs-93-gas.html and it doesn't seem that 91 octane would be the main culprit to your issue. You possibly could of gotten some bad gas but it sounds like it could be something else.

Maybe try and get an extended warranty from somewhere (might be hard but worth it) just in case.

CarPartsDiscount.com

there is a very low tech way to check for a vacuum leak, if you spray starting fluid in different parts of your engine and suddenly the idle picks up then you have found that you have a leak. you can begin to narrow it down from there. The downside to doing this on a newer vehicle is they have a lot of plastic under the hood and this can tarnish or damage the plastic so i would save this for a last resort type situation. Plus with this new of a vehicle, chances are there is'nt a leak, i would suspect a sensor of some sort to cause the issue.

m a x i m u s

Could be a bad spark plug, plug wire or coil pack. Is it rhythmic? Does it seem to happen at the same point in the cycle? I had a funky idle in another car before and it was a bad spark plug wire.

sdenney89

. Your touching button too hard,,,,next time pull up on button 1/2 way, gently ,and you'll see that it won't slide down anymore pull up hard and and window will leave a 1 in gap,

JoshBlond

Thanks for all the input guys. Just got back from a buddies indie shop and he has a pretty advanced scanner that monitors the vehicle for an amount of time and it couldn't find any misfires or leaks. They told me exactly what mercedes did that with such little chassis you will feel the motor. Maybe i'm just over reacting. I remember my w211 e63 doing the same. All your motors stay very smooth all the time or can you feel little vibration?

INS1GNIA

I feel some vibration when stopped occasionally, but I like to think of it as the car giving me a massage and whispering sweet nothings.

JoshBlond

lol yeah i always hope for sweet things. your not too far from me. im over here in OP. ever go to fast fridays?