amg8

So I am driving a MY17 C63s and when I first got it, all the power is there. On the freeway at around 65mph, I can floor it passed kickdown and the wheels would chirp in Sport+.

Recently I feel the loss of power. It just doesn't pull as hard as it used to and no it is not because I got used to it.

I can see the on screen HP and TQ and it would both hit at max but only for about 2 full seconds and it would start to decline. It didn't use to do that.

I have not gotten any updates to my ECU so that is not it.

Not sure if anyone else had experienced this?

mazyo

This sounds like what happened to me when the battery was drained while the car was being detailed. When the battery is low it puts the car in a sort of limp mode and feels like driving with the emergency brake on (especially in first and second gear).
I can also be caused if you leave the key fob in the car for long periods of time, leave the lights on or door open.

The only way to fix this is have the dealer or Mercedes mechanic reboot all the systems.

amg8

Thanks for the reply but I am not sure my issue is the exact same. I don't feel like driving with the emergency brakes on. I feel like the car has like 100 hp less is all.

mazyo

Maybe I did not describe it right because what you said in your original post sounds exactly like my car felt

amg8

So are you saying your battery discharged to a level where it put the car in permanent limp mode and only rebooting the system will reset that?

Were you seeing full 500~ HP and 500~ TQ in the display when flooring it?

auditoamg

Many of us are having this same problem.
Nothing to do with voltage.
I have no under voltage codes and it feels this way.

amg8

The issues I have read by searching are either after some update to the ECU or they're not seeing full HP/TQ which none applies to me.

What are some other symptoms are you seeing? And did your car ever feel proper when you first got it?

usaviking

Mine shows the full HP in the display (got to 492 last time I floored it on the highway) but it just feels underpowered for a 500 hp car. Not "handbrake is on" kind of underpowered. I got it new in June and it's always felt that way. It feels fine in higher gears but 1st and 2nd are kinda docile IMO. My tires don't chirp very easily and most certainly not at 65 mph

ezatnova

Your “problem” is just the newer software that your June car came with. Sadly that’s how they are now. Pretty wimpy feeing from a stop in first and second, and no longer will snap the rear loose on a highway kickdown at 60-70 mph.

auditoamg

^^^^^ this.... 😢

zdonner

Disabled the Traction control and try the same thing - sounds like the TC/SCM kicking in, this doesn't always trigger the light to blink on all modern cars.

With the TC on the car feels like it has Boost by Gear and doesn't wake up until it gets into the 3-4 gear due to anticipated or actual traction issues.

At least that's my experience.

munis

What you are describing is exactly what I experienced as well and it is exactly like what Mazyo is talking about. Both of you are talking about the same thing. The car is in a limp mode. May be you did not drive the car for a while and the battery was low, so the car entered a limp mode. Only way to get rid of it is have the dealer access your ECU and TCU and reset all the systems. All of them.

This fixed it for me. Also this is not caused only by a low battery. If your ECU has any secondary error codes (codes that are there but does not cause check engine light), some of them might trigger limp mode as well.

I know exactly what you are talking about. Happened to me last week as well. It is all fixed now. My car was putting down 100hp less and 150 trq less than the regular numbers I am used to.


I will upload a video when I can.

amg8

Ok so after having search the entire internet on this issue I was willing to try anything.

So I self reseted the ECU/Trans and took it for a test drive. Initial test is telling me some of the power is back. I tested on surface streets and on the highway. The rear does step out and the traction control light does come on when flooring it from a dead stop or under ~10mph.

On the highway, it does pull harder now however it is still not the same as before when I first got the car. I also noticed after the reset, HP on the comand screen does not hit max anymore. Very close maybe 480 - 490 but doesn't hit max and thats same with TQ. Not sure why.

Now being paranoid that it is not what it once was, I am starting to think perhaps I have a boost leak some where...

I am not 100% sure the reset actually changed something or it is just a coincidence but it may be worth a try for you folks.

SELF RESET PROCEDURE:

1. Close all windows, turn off all electronics like your comand and AC.
2. Turn key to position 2 without cranking the engine over.
3. Depress gas pedal all the way down passed the kickdown button.
4. Wait 15 seconds.
5. Turn key to off position but don't take out the key.
6. Release gas pedal.
7. Wait 5 mins for ECU/ECM to reset. Don't touch anything in the car while you wait. As in don't turn on anything or open the door.
8. After 5 mins passed, go ahead and restart the car and take it for a spin.
9. Report back so all of us can benefit from.

mazyo

I did not have any error codes either, at least not on the dash or in the settings.

ezatnova

Interesting. Haven’t done this but I have disconnected the battery overnight and it didn’t change anything at all.

If you do the procedure you detailed here, doesn’t put the car back to factory settings? (As in deletes all settings saved for the car, entertainment, etc etc)

munis

Guys just letting you know. The self ECU/TCU Reset process that you just described does not work at all. Atleast not for me. It might have been working on the older models.

Also please note, disconnecting the battery does not work either, which I tried as well. Apparently some of the control units have some kind of a back up power for memory. You need to be connected to Xentry for this and you need to reset all the systems that way. Just take it to the dealership. It takes 30 minutes tops. My car was completely back to normal and pulls harder than ever.

amg8

No it does not.

auditoamg

It also doesn't resolve it... 😂

amg8

FYI: http://www.mercedesmedic.com/reset-m...-instructions/

auditoamg

It does not resolve the problem described, however.

mazyo

I was told by the mechanic that fixed this issue in my car that a simple reset as does not fix the issue. He said each of the systems(I think he said 6 resets all together) needs to be reset and can only be done by Mercedes or certified Merc Service center/mechanic .

You would think that something that puts the car into limp mode would at least show an error somewhere so we would know that there is an issue. It must happen a lot becasue the mechanic diagnosed it as soon as I told him the issue.

amg8

Can you please provide the invoice documenting what the dealer did for you so we could show our dealers the same?

auditoamg

I've asked my dealer to do it and they stare at me blankly....

ItalianJoe1

If there's anything to reset, it's the adaptation values in the M/E. I can't see how it's adapting down to lesser power, that just seems backwards. Normally a reset of adaptations is only done when you replace a major component. It's not about power output, but smoothness and specific adjustments for production tolerances.

amg8

Just to give an update here. After taking in the car, the dealer hooked it up to their diagnostics and said there were no updates available and that the car has the latest software. So basically there is nothing they can do for me.