During acceleration or normal driving my 03 e55 feels very jerky. What could cause this? Oil change or transmission fluid change needed? SC belt slipping? I have 33k mi right now

 

Probably the SC clutch engaging.See if it drives smoother in C mode instead of S mode.

 

Tried it on C mode too and still the same result.

 

Are you familiar with the characteristics of the super chargers clutch engagement? The belt might be slipping,look on the front of the motor where the belt rides and see if there is alot of black belt residue around the pulley.Is the CEL coming on at all?An oil change wont fix this problem but if the trans is hurt you might want to get it looked at soon,or you might get stranded.My guess is that its not the trans though,they seem to be fairly bullet proof,but you never know.You really need to have a tech look at it,could be anyting really.

 

I'm not familiar with the characteristics of the superchargers clutch engagement, is this normal? The CEL light does not come on. I'll check for black residue in the morning to see if the belt is slipping. I was planning on driving the 55 this weekend but I don't want to risk being stranded on the way. I made an appointment at mercedes for tuesday to get it all looked at so the beast will have to sleep out this holiday weekend

 

I think it is the supercharger ('SC') engagement as well. Here's some info I've posted in the past -

>>>
So, the first thing I recommend is that you drive around a bit in Manual "M" mode to get a feel for how much throttle it takes in each gear to get the SC to engage.

If you pull away with very light throttle to keep the SC from engaging and then bring on the throttle in fourth gear, you will notice that the transition is smooth and occurs at a low RPM (~1000). You are in fourth gear and the motor has a higher load demand, so the ECU engages the SC early.
>>>

I believe the belt slipping is a contributor to the "sputtering and jerky" item you noticed, but I'm coming to the conclusion that it is more a product of the SC engagement in first or second gear. Plus, I'm trying to figure out a way to solve the problem without continually changing belts or supercharger clutch packs (which I think is a symptom and not a solution).

When enough throttle is applied to engage the SC, the engine computer "kicks-up" the engine to compensate for the added accessory load, the drag of the SC engagement momentarily pulls down the engine RPM gain, then the engine starts to race back up.

In the current Chicagoland winter wet weather conditions, the jerkiness of the SC goes away if the tires slip when the SC engagement occurs.

One thing you can try, I find this helps in daily driving -
1. Gently get the car rolling in first gear without engaging the SC,
2. Let the car shift gently into second,
3. Once the second gear shift completes feed in just enough throttle to engage the SC.

Course, an unplanned event causes those three steps to be difficult.

I'm currently trying to figure out how to hack the adaptation channels that basically mimic what is the "accelerator pump" function in the engine computer to solve this problem. I'll either hit pay dirt, or have a complete miss.

 

It's funny cause I seem to have this problem too. At first I thought it could be the differential because the car would stumble and I would hear a humming sound coming from ther rear.

I just took the car into the dealer and they replaced the supercharger clutch with the new updated version (kevlar). As soon as I drove out of the dealership, I couldn't really feel the stumbling but still heard the humming sound. It's like a humming/moaning sound and it seems to be coming from the rear. And it seems like it only happens on light throttle in the first 2 gears (approx. @ 1000 - 1500 rpm).

 

I hear that humming sound coming on and off too. It sounds like a struggling humming even while I'm cruising on 5th gear. What is the humming? Is it the intercooler pump?

 

Sounds like you have water in the Transmission.

The tranz cooling radiator is located inside the main engine radiator.

Apparently there was a faulty batch of radiators in the earlier Euro models 02-03 which the tranz section ruptured and allowed water to contaminate the tranz oil.

This happened to me twice and was repaired under warranty.

Work involved: Replace main Radiator & Torque converter, rebuild Transmission, flush Engine block.

I hope yours is still under warranty.

 

Yes mine is still under warranty, what is downtime for repairs on all of this usually? I need to extend my warranty too