RawBenz

I've noticed in my wife's C63 that when it's been driven for a while during the day and it's hot, it shakes and the revs go up and down.

Also on idle i've noticed from standing on the outside of the car the idle keeps going up and down. The engine idle goes up and down.

Also i've noticed when the car is parked in traffic on a downhill it likes to shake when hot.

MAF Sensor?
Plugs? (they were changed 10 000km's ago)
02 Sensor?

solekeeper

any codes thrown, no way to tell unless otherwise..

CarHopper

MAFs, plugs, cam sensors...

Really hard to tell with no CELs. And taking it to the dealer with that list gets expensive quickly as they'll check everything.

RawBenz

Nothing has come up on the dash..
Can i get Mercedes to check for codes?

Also could it be exhaust leak? I don't know i just have a feeling that it could be an exhaust leak for some reason.

rentzington

Using good high octane fuel?

Also you should be able to buy a odb code reader and drive with it connected see if you get any codes

RawBenz

Yeah always use high octane. Here in Aus we have pretty good fuel too. Always use 98.

m a x i m u s

Codes can still show up with a scanner even if it didn't trip the CEL. Here in the US, some stores will check for free. Or buy an OBD2 scanner and check it yourself. You can get an inexpensive one and I've found it very handy to have one.

rentzington

and if youve bought a eurocharged tune then you already have a scanner in the mygenius unit.

abcut973

Could be anything from leak to misfire via MAFs or O2 sensors as well as bad gas.
So get it scanned. GL

ToXicXxX

Vague post is vague...

F1BHP

Throttle position sensor. Engine or trans mounts. Fuel filter

Petakii63

How do you use it to scan?

Jasonoff

+1

rentzington

I don't remeber the exact options but there is a data capture mode in the menu, or called something similar like data log
i know it will capture information on the vehicle, pretty sure it would show codes.

Kid Dynamite

iTrader: (1)

In German mb forum some user had this problem too.....it was a faulty inlet manifold gasket.

Dont know it 100% in your chase but mb/amg has changed the part number of the gasket a couple of times

SROC276

I just had my fuel check valve and fuel pumps changed out. Idling was rough and would have violent engine shakes that came along a check light. Concerning your issue, this could be a possibility. Would do a fuel pressure check and see how it is during idle.

ToXicXxX

Mine had that issue. Didn't rattle, but it was always searching for idle RPM, and would go into limp when pushed hard.

ChrisC0863

I just went through a similar symptom....turned out to be 2 bad throttle actuators for me. RPM's would bounce while driving, car would go into limp mode while driving.... Sometimes my CEL would come on, sometimes it wouldn't.

RawBenz

How do you know if it goes into limp mode?

abcut973

Loss of power no matter how mad you hit the throttle

ChrisC0863

This.... No power and mine would sound like it was choking for fuel.

RawBenz

Took the car to mercedes, checked for codes and it was all clear.
No codes at all.

Still notice by standing outside the car that the engine revs keep going up and down.
Needle only moves slightly, but you can hear the engine isn't stable on a certain rpm. It keeps fluctuating up and down..

It sounds like someone is slightly putting their foot on the accelerator then letting go, and repeating.

bhamg

When my car went into limp mode and I pulled the plugs Bank 1 had been shut down completely. Only Bank 2 fired, so it was no surprise the engine had no power whatsoever and was massively lumpy in operation. Is that standard limp mode operation or are there different limp modes based on what the codes indicate?

abcut973

Does this happen only when the engine is warm?

RawBenz

Yes.
After initial startup when the needle steadies, it's fine.. until it gets warm/hot or unless it's been driven hard.

Then it starts to fluctuate up and down.