Kumar Goswami

I have a 2011 E550 -- until about 2 months ago I could not believe the acceleration. Press the gas and before you know it you are going 90mph. On the highway I felt like it would just take off and unless I paid attention to it. But now it seems sluggish and soft. It still has pep but it's not like i need to hold it back. Rather I need to yell "mush" more often and persuade it to go fast. It's just not as peppy.

I've been servicing it as required and mostly I use it around town and to go to work which requires about 15min on the highway.

Have any of you have a similar experience? Any ideas on what it might be? Do I need to change the spark plugs or something???

thefisch

Give the ECU reset a try. I do it every 6 months or so whenever it starts to feel less responsive. Copied this from another post so sorry I cannot give credit or take credit.

1. Get in car and close the door.
2. Turn key to position 2 (or press the start button twice) with feet off the pedals, i.e. do NOT start the engine.
3. Floor the gas pedal and keep it down waiting 10 seconds when you will turn the key to position 1 (or press the start button once) still keeping the gas pedal down.
4. After key in position 1 lift you foot from the gas pedal and wait about two minutes. In my car the cluster goes black after about 20 seconds but then pops up again after about two minutes. Anyhow, wait two minutes no matter what happens.
5. Turn key off.

pacrimguru

What is an ECU reset supposed to do? I bought a used E350 and haven't done this yet. Is this the same procedure to reset the transmission "memory"?

Abrown3mtg

yes it is!

Kumar Goswami

Many thanks for this! I'll give it a try once I fix my dead battery. I'll let you know how it goes.

pacrimguru

I also saw these instructions in another thread... anyone know which version is correct? Is there any feedback after its been reset? I tried both versions but it didn't react in any way.

With the Keyless Go button inserted:

1) foot off the brake during the whole procedure
2) press the Keyless Go Start button once
3) press the accelerator to the floor and hold for 5 seconds
4) press the Keyless Go Start button twice to turn off the ignition
5) release the gas pedal
6) Wait at least two minutes before starting the car.

The Keyless Go Start button does come out of the ignition switch - it may be a little hard to get out but I was able to pop mine out with a little effort. Then follow the normal procedure:

1) ignition switch to position 1
2) push the gas pedal to the floor and hold for 5 seconds
3) turn the ignition switch to the off (0) position
4) release the gas pedal
5) wait at least two minutes before starting the car.

MBSebas87

is this the same as the TCU reset? I know what the ECU is but I thought the TCU was different.

thefisch

This procedure does effect the shift points of the tranny for me so I guess you could call it TCU. I just kept referring to it as ECU since that's how it was referred to when I looked it up.

There is no feedback that I can tell other than how the car drives afterwards and I can always tell the difference. The two versions you posted both have the ignition in position 1 (radio, no fan blower) and only hold the pedal down for 5 seconds. The one I used has the key in position 2 where the climate fan is blowing and the pedal down for 10. Not sure if that makes a difference.

pacrimguru

Thanks for the feedback! I'll try both and see what happens.

g4benz

Is this how easy it is for anyone to reset the ECU? My car is tuned, so my ECU is modified. So, if someone did this procedure to my car, bye bye to the tune? Hmm..

thefisch

I doubt it would impact a tune. But if you have a tune, I doubt you would need it. Perhaps the tune overrides the adaptive nature of the tranny.

rediesel

It won't erase a tune. It's more of a TCU reset than and ECU, but mostly resets the learned throttle adaptions. You could also start driving more aggressively and it will adapt as well. Frankly if you have a dead battery it might reset anyway.

pamiboy

Now, will this ECU reset affect the operation / calibration of any functions other than the transmission such as the windows, sunroof, etc.

thefisch

Someone posted that they couldn't get their sunroof to close all the way no matter what tried. Then they shared that this ECU/TCU reset fixed it for them.

I have never done it with the windows/sunroof open and I have not had an issue afterwards. Other than that one comment noted above, I have only seen posts about it affecting throttle response and shift points.

g4benz

Gotcha - I was thinking this procedure would be too simple to erase a CPU reprogram (tune). Phew..

g4benz

Yes, I was just curious. Like going to a dealer, and one of the technicians deciding to reset the ECU (using the method listed) without telling me..and there goes my tune..haha..can't be that simple though..

thefisch

Don't some tunes come with a loader that you can use via android to switch versions, etc. If yours has to be done at a shop, I would think they would redo it for you if it got erased. No?

g4benz

Not sure actually. The tune is by Renntech. I think the shop (i.e. dealer) would need to work with Renntech to get it re-tuned. The dual-boot system you speak of does make sense, but not sure if that's how it works.

KY.Benzster

THANK YOU THANK YOU THANK YOU!!!

For 2 years now I've just chalked it up that E's had rough transmission shifts until I performed the reset yesterday. Wow, what a difference! Loving my car all over again...no more jerking down shifts & smoother/higher shift points. Great forum posts fellas.

thefisch

Glad it helped you. But I can't take credit for it as I found the instructions on the forum here.

I hope the fix sticks for you and does not return. Obviously you could do the procedure again. But my concern for you is that there is a larger problem looming with past rough shift points. It's seems illogical that an adaptive feature would lead to roughness. Instead I worry that your tranny just has problems with lower shift points and the reset raised them for you. Time will tell.

My understanding is that the adaptive transmission is designed to tailor to the driver's style so the more leisurely you drive the lower the shift points. After a reset, I notice it holds the gear longer when I drive slowly (like an old man according to my wife). But I like it that way. Over time it starts to anticipate that and shift earlier and eventually I get frustrated having to mash the pedal for a 'proper' reaction. Then I remember to do a reset and it feels like a new car. Personally I would rather the car stay the same and let my right foot adapt depending on the situation rather than the other way around.

KY.Benzster

Thanks for the detailed response. When I say "rough" I don't truly mean rough. In Layman's terms, I could feel the car shifting from time to time & at times (when coming to an abrupt stop in Sports mode) my car would downshift in a jerky manner (mostly 3rd down to 2nd). I wanted my luxury car to feel more luxury when shifting and during the last 24hrs it's felt like a dream. The only thing I can think is my car's previous owner was an elderly woman & I simply got her shift points until yesterday's reset.

pamiboy

May be I should also try it then. My transmission occasionally jerks while slowing down without braking (climbing uphill).