I recently purchased a 2011 E350 with around 61,000 miles and I noticed that the tachometer will fluctuate up and down about 100 RPM. This happens while driving at a constant speed and with steady throttle input. I saw a old post on here that described a similar issue but I'm not sure what they found. I dropped it off at the dealership this morning for diagnosis. I will post the findings when I hear back from Mercedes for those who may be suffering from similar issues.

 

 

Very odd, I don't know if I've seen this happen on any vehicle before. Keep us in tuned, I hope it's nothing really.

 

+1 That's is very odd. At least your getting great gas mileage at highway speed.

 

I just picked up the car right as they were closing. They told me the instrument cluster software needed to be updated. So they performed a flash of the instrument cluster as per LI54.30-P-049068. As soon as I left the dealership and got up to around 45 mph the tach began fluctuating again. The flash of the IC did nothing to resolve my issue and now I'm pissed because this tells me that they didn't even test to see if their solution fixed the issue... I will be calling them again in the morning to discuss my findings with the service advisor.

 

I have a 2 year extended warranty and they did not charge me anything.

Does anyone have any info about LI54.30-P-049068?

 

I'm sure you have but just in case a google search brought this up. http://workshop-manuals.com/mercedes...pprox._100rpm/

 

Yeah I saw that but I wasn't sure if the dealership had access to more details.
My VIN is A271455 which, if I'm looking at it correctly, is outside of the VINs effected?

 

The link you sent describes the tach fluctuating at an idle. My tach works fine at an idle. It only fluctuates while I'm driving at constant speeds.

 

I have had this before turned out to be a turbo pressure problem according to DAS STAR . I have not replaced the part because we thought this might be a glitch or something a bad signal from the performance kit .

The frequency of this problem happening has dramatically diminished almost "extirpated" since we switched to premium Shell or BP .
To make your mind ease , my car was jerking and worse than yours and tranny were stuck in either 2 or 3

 

What speed is the car going with only 900 - 1000 rpm?


For troubleshooting it, do you feel any speed change while this happens?


Have you tried to drive with transmission in manual mode, i.e. when you drive and see this rpm needle jumping pull the left side shifter paddle quickly once? This would set the gear one lower than what is in use while driving.


I'm thinking here if the transmission is shifting between two gears? It seems too high frequency for this though but if going to manual mode stops the problem then it is somehow transmission related.

 

-I was driving at about 40 mph in the video.
-I do not feel any speed change when the fluctuations are occurring.
-I have not tried to shift into manual mode but I will try it on Monday on the way to work. Thanks for the suggestion.

 

-Correction* I was driving at about 20 mph in the video not 40...

I tried selecting lower gears using the paddles and the rpm's continued to fluctuate until they exceeded roughly 3,000. After the needle passed 3,000 it was smooth and no longer fluctuated. At the 3,000 rpm position the needle is at a relatively high angle whereas when it is at 1,000 rpm it is relatively flat. So it is almost as if the tach (or motor controlling the tach) has slack in it when the needle is horizontal allowing it to bounce around.

 

I dropped it off at the dealership this morning. I will update when I pick the car up later.

 

What ended up being the solution?

 

The dealership told me that the fluctuations were within tolerance. I asked, "Oh yeah? Can you show me the tolerance from Mercedes?". They could not provide any document stating what the acceptable tolerance was. They told me there is nothing they can do. Now my car is no longer under warranty and the tach is still bouncing just as bad as ever.

 

Wow...one more time realized that MB dealership dont carr much about customers and treat them like its nothing... ugh

 

sorry to hear about your problem and ill be very disappointed too to say the least.

anyways, you/dealership have documentation that the problem started whilst the car was still under warranty. (referring to your post #6 last 8/13/2015 )
if that was down here, they should still be liable for repairs for free since they didnt fix it back when it was still covered under warranty. just my 2 cents.

hope you can get it fixed soon mate. best of luck!

 

My E350 4matic does the same thing...very odd

 

Quote:

Originally Posted by cguid32

I dropped it off at the dealership this morning. I will update when I pick the car up later.

I recently had the worst experience at MB Dealer. My car was great it had no issues at all but the check engine light came on due to putting Gas while engine was on which is weird but light went on. So I Took the car to get it checked and while being there they told me that my car needed a B service done because it reach the 60k miles. Long story short The car had the service done and now im having that same fluctuating issue. I accelerate and it needle goes up and down like wth my car never did that and now is doing it after picking it up from dealer. They told me the same they don’t know what’s causing the car to do that. I will upload a video once I drive back home work

 

Hi has anybody fix the the problem with the fluctuating rpm?

 

I'm also interested in finding out if this problem was fixed and if so, what was the actual problem, i just bought a 2011 E350 and while driving i noticed the same issue where the rpms go up and down while driving at a steady speed, is not very noticeable but I can feel the car speed fluctuate by the same amount and I can hear the car jerking up and down as well.

I have read many other posts and I am beginning to lean towards a transmission issue, i have read somewhere this is a very common problem with these cars, i read somewhere also that it might be a bad solenoid, there's no error code or anything, I bought a very nice scanner which can read and control most of the control modules in this car and couldn't find any code related to the transmission.

It would be very nice to hear from someone else with a similar issue before I decide to drop the transmission myself and try to investigate in more detail what's going on.

Walter

 

This is going to be another interesting hunt for a known fix.
The question is how fast can a motivated group connect all the dots.

Doesn't this seems like a tranny shaft sensor getting skewed by magnetized sludge or the crankshaft sensor?

 

Yes, I was wondering that as well, I wonder where the tach gets it's electronic input reading from? The CPS?

 

Why has not anyone confirm yet this RPM fluctuation using a 2nd digital gauge OBD2 type vs the mechanical tacho at instrument cluster ?
If there is no mild jerking or any mechanical feel that indeed the engine has fluctuating RPM, it could be the tacho itself fluctuating its value.
OP did not mention he felt a kind of engine "hunting" of 100 RPM , he kept mentioning only visual value of the RPM.