Hey all, first time poster here. I recently purchased a 2010 E63 with P30 package and 85k miles and I'm having an odd issue. Any insight would be greatly appreciated! I'll try to be as detailed at possible with the description.

In layman's terms, my issue is an RPM surging when throttle is less than 50%. It is most prominent in Comfort mode, but is evident in all other modes including manual mode. The car will surge and RPMs bounce around as if there is a misfire or the transmission is slipping. It performs perfectly at higher throttle positions and the transmission does not slip. It does it lightly when the car is cold but gets progressively worse as the car reaches operating temperature. I will attach a video below, although it is WAY more extreme in person. You can hear the car surge and watch the RPMs bounce. It even has a slightly different sound, almost like increased induction? Hard to describe, but I think it's noticeable in the video. I am holding a steady ~25% throttle position in the video. https://drive.google.com/file/d/1Axo308RF0662lyBWYL29aYtsz1zPl1IV/view?usp=sharing

The car has MBH longitude headers, an x pipe, flow master 200 cell secondary cats and apparently has a tune from MBH. Otherwise it is stock. I haven't found a way to verify that it has a tune, but considering the fuel trims; I believe it is still tuned.

I just went through the car to do some maintenance in hopes that one of these things would be my issue. I replaced these items:
- Injectors
- Cleaned PCV valve, intake manifold, and throttle bodies (minimal corrosion on throttle body plate, not enough to cause this)
- Intake manifold gaskets
- Cleaned mass air flow sensors
- OEM air filters
- Transmission Service (done properly)
- Rear diff service

It does have P0420 and P0430 codes, but I account that to the high-flow cats. No other codes. I checked the plugs, they are OE and clean. Coils are also OE, unsure of age.

My current theories:
- The tune was wiped somehow
- Vacuum leak (have not smoke tested yet)
- O2 sensors
- Clogged cats

I've searched high and low for someone with similar issues and haven't found anything similar. I hope someone has some insight. Thanks in advance!

 

Interesting. Hard to tell from the video but seem like the converter is locking/unlocking?
I would rev it to the same rpm in Park and see what happens. Then hold the brake in Drive, while stopped, and power brake to that rpm. The engine won't know the difference but at 0mph the converter will remain unlocked.
Kinda doubt the trans is slipping. Possible, sure, just unlikely based on your description. The converter on the other hand would, imo, do exactly that.

 

Could be your wet clutch... either needs re adaptation or worn, but I doubt it ... seems like you're on to the right things with what you listed

 

I'm not sure I fully understand the MCT trans. I know that it is a wet clutch system, and I was under the impression that there was no torque converter.

I tried re adaptation with the throttle procedure and it didn't make a difference unfortunately. I also left the battery unhooked overnight to try and reset as many systems as I could.

I'm going to try and find someone that's an expert with M156 / MCT transmissions and see if I can pay for some insight. Thanks guys.

 

wet clutch can be re adapted with xentry

https://mbworld.org/forums/w212-amg/...r-service.html