amg8

Just to note, this power loss issue happened to me again. I am only guessing here as I don't have any concrete evidence on what is actually causing the issue but I do have 2 cellink b batteries that powers my dashcams during park mode and they're only charged when ACC is on. I am guessing it is drawing too much power even though the car is running and the car doesn't like that OR it is when the car engine is not on but ACC is still on. What do I mean by that, when you come to a stop and park your car ( depressed start/stop ) to shut the engine, ACC is actually still on for a long while unless you open your doors. Hence the radio keeps playing. I haven't thought of this before and perhaps it is drawing too much power to charge the cellink b batteries. So those are my two guesses as to what is going on.

So this time around I have removed the cellink b batteries and will go in to get my ECU reprogrammed again and observe if/when this happens again. That will tell me if that is the cause. Note that I still have my dashcams wired up to ACC on though.

Just to put more information down. My battery level when car is cold and not started is 12.52v and on a cold crank it drops to 10.4v which to me seems abit low. But I would think the car is smarter than I am if low voltage on battery was indeed detected, it would show the battery warning light...Also I used a OBDII tool made for Mercedes and I could not get any code from the system about this so that is also strange. Perhaps this could only be found from Xentry DAS. Again I don't know and just grasping at straws here to eventually get to the bottom of the issue.

Modio1234

I had my battery pretty low to the point it told me to start the car now in the display. Im pretty sure I have all 500hp but maybe I don't and thats the reason I'm looking into a tune now. To add I also have some bad first gear turbo lag.

HarrySeaward

There must be something going on...

I am befuddled by posts talking about turbo lag, loss of power, etc... and I have experienced none thus far. People post great, legit stock 1/4 mile numbers and others have $80k junkers. The fact that most of the dealerships have no answer is also worrisome.

Granted I have less than 2k miles on mine, but it seems almost as if people are driving completely different vehicles from one another.

"Limp Mode" seems like the common description, but it seems that it is likely multifactorial and not only limited to periodic low battery issues.

BrownDog09

Agreed. I have 1100 miles on my S coupe and I am so impressed with fit and finish and the mountains of power.

I have been been wondering how many of these cases are the results of modifications, tunes, flashing/reflashing, questionable piggybacks etc.

koifysh

Quick Update: I found a local private Mercedes mechanic and he hook the car up using xentry, and found a bunch of error code on battery voltages, deleted that and did a quick reset (not sure if he did a reset on all the system). The car doesn't idle rough anymore in park, before I can feel the rough idling in my seats, gear box downshift from 2nd to 1st is much smoother, and most importantly the car pulls like how a v8 should! and it is more responsive in any mode. I'm so glad forum like this exist! I actually insisted the dealer to hook the car up and do a reset but the said no battery voltages error code or anything... I don't understand how none of the so called "amg specialist", don't know anything about this.

amg8

Yeah same with me when I went to the dealer, they said they found nothing wrong!!! In addition, its funny how when I hooked it up to my OBD tool (iCarsoft for Mercedes) it doesn't find any fault codes relating to voltages.

HarrySeaward

I apologize if this has already been addressed, but I have a few questions (genuine interest and no sarcasm inferred):

Do the MB service people not use Xentry?

Do/did you have any accessories that could have caused the battery voltage issues?

Have you modded your C63 at all?

I am sorry for beating a dead horse, but there has been enough smoke to raise concern for fire.

Thanks in advance.

koifysh

I don't know what they use, didn't ask. They told me they plug it in their diagnostic system and found nothing, but the private mb mechanic plug it in using xentry show me that there was a few error code on voltages

I don't have any kind of accessories that would have caused voltage issues. The only thing I did was sitting in the car for a few hours when I first got it to figure out the command system, plus every other day to show friends and families the interior and the people who tinted my car left the key in the car with all the lights on for 2 hours. After that the car doesn't pull as hard as before when I give it the same amount of throttle at 60 mph.

My c63s is 100% stock

All I can say is taking her to a local mb mechanic to do a reset and delete some faulty codes fixed everything for me including rough idling and downshift from 2 to 1st is very smooth and barely noticeable.

amg8

I just came back from my local mechanic, he hooked it up to Xentry and found the same low voltage issues logged as I had before. He said normal OBDII tool will not see this code, only with a Xentry according to him. He says any of the following can cause this.

• When you get a car wash and they leave the door unlocked/opened with key fob near by.
• Using the accessories for too long without engine started.
• Additional accessories that draws too much voltage. radars, jammers, dashcams...etc.

For context, my car is bone stock other than running a dashcam.

amg8

The frustrating thing about this is there is no indication anywhere that will tell you you're in "powerless" mode other than your butt dyno AND once that low voltage code is logged, it will never resolve itself overtime unless you reset the system and only via Xentry which is not as easy to obtain ( legitimate ones anyways ).

HarrySeaward

Thanks for the further details. The "opened" part must be more important than the unlocked part because my car is constantly unlocked when in my garage and the FOB is in the car. I have gone a week without driving, have left FOB in car the entire time, and havn't had it go limp *insert joke here*.

amg8

More information on how I determine the power loss is not in the low end but the higher end. I can tell right away if I do 50/60mph pull to 80mph. I can feel it isn't making much power from that pull so right away I know its in a "limp" mode. It feels like I lost 150/200 hp. After the reset, it pulls hard like it is supposed to.

HarrySeaward

Glad you are finally driving the same vehicle I am. Will be taking mine in soon for the 1.875k mile service. I like my C63S more overall than my 2015 M4.

That being said, the service through BMW has been better, is included, and came with more "concierge services" without paying more.

Still waiting for the perfect 2+2 coupe, but it doesn't exist to this point.

munis

If you want to know it for sure, just turn on the AMG Dynamic select engine info on. If your car is a semi limp mode where you have a power loss, you will see that the power is capped to a certain limit and no matter what you do the car would not give you the full power.

amg8

I wish it was that easy however it doesn't work like that in this case. I had a limp mode even when the "gimmicky" display shows 500 hp.

NSAMG

So. I had my ECU reflashed back to stock, and dyno'd again. After having the fault code P061A62 removed (the red line on the graph). The horse power went down 27, which is understandable, as I had the tune removed. However, the torque went up 123? So, then I had the tune reinstalled in the ECU, and re-dyno'd......and, as you can see, the Horsepower went back up to 523 and the torque to 534! The graph doesn't seem right to me, or is this the way the Mercedes is......that you don't burn your tires off starting off?

ezatnova

Fame Douglas

VaserC63S

I had this issue with the car brand new. In my case it not only idled rough, it would stall and refuse to start or start only randomly. They replaced the battery with a new one and problem solved. I have a dashcam too, but have not had the problem come back. You wont believe this, but my Range Rover had similar issues including self shifting to park and getting stuck in park, and it turned out to be bad battery. The Rover is september 2015 build with 21000 miles now. Needed new battery at 18000 miles. My AMG needed it with only 20 miles on the car.

It's not just AMG, its all these new cars with a ton of computers onboard. Low voltage causes very weird behavior.

Rippe

Could somebody give the exact abbreviation of the low volt code so that I could give it to the garage and ask them to check my car in order to see whether this specific code is there?

amg8

Thanks for sharing. Couple of follow up questions for you if you don't mind.

1. Did the tech say they found any fault code in the system?
2. Did you replace the main battery only or both the aux and main battery?
3. Did you use OEM replacement?

Gungaslow

Gungaslow

bk_E63S

Were you ever able to figure what the issue was? I have a 2018 e63s with the same issue, i feel like it's not pulling to its full potential and or may be there is a loss of power...i spoke to a few friends and they said maybe it can be the spark plugs?? any help would be appreeciated

Damien T

Did you ever get this issue solved? i am currently going through this problem right now, Hits 480 hp for 2 seconds and it goes back down to 300