Hi everyone.

I have a 2007 C200 Kompressor (W204) with the M271 1.8 supercharged engine.
It has the 5-speed automatic transmission.

The car has a VERY annoying problem which has proven to be very hard to diagnose.
I have attached a video of the problem.

When driving slow with only minor throttle and low rpms, the rpm needle is jumping up and down and you can actually feel the car "chug / bounce" back and forth along with the rpm jumping. It is not a lot, but it is definitely enough to feel it on the car and when driving slow in cues, it is sooooo annoying.

I can make it go away by pressing the accelerator pedal a little more or a little less. It's like the pedal has a spot, where it gets confused and starts to fluctuate, and when pressing a 2% more on the pedal or just ease off 2%, then it pretty much stabilizes and feels ok.
When I start the car cold, it seems to vibrate a little at idle and if I put the gear in Reverse right after starting, but keep my food on the brake the vibration gets much worse and the rpm needle jumps as well. If I just let the car idle for 1 minute before doing anything, then all seems fine when putting it into reverse and hold the brake. Does not vibrate nearly as much and actually feels pretty "normal".

- I have had the car in a MB diagnose and no error codes or anything.
- I have changed spark plugs.
- I have replaced the engine oil and oil filter.
- I have sprayed the MAF sensor with cleaner.
- I have had the A/C compressor replaced under warranty.
- I have had the Auto transmission fluid replaced by Mercedes Benz shop.
- I have had the dreaded chain replaced.
- I have had a compression test done on the engine, and all seemed fine.
- I have done a reset on the TB / Transmission with the ignition / keep pedal pressed and wait 2 mins procedure.

Now I'm pretty much stumped ... and don't really know where to go from here.
It would think, that if the MAF (or any other sensor) is faulty it would bring up the Engine Check Light or at the very least, throw up an error code.

I'm at the end of my ropes and this is really affecting my love towards the car. I do love it, but I hate the fact that something isn't right and MB and two other garages has not been able to diagnose it. :/

Has anyone seen something like this or similar before ? ...
ANY advice or things to try out will be GREATLY appreciated.

SEE VIDEO:



Thanks
/Thomas

 

I have a 2009 C300 with the 3.0L M272 V6 and I've recently noticed the same, if not slightly less, fluttering of the rpm needle. This seemed to have happened after a friend accidentally gave me a gallon of water instead of gasoline. The car would violently shake and misfire for a few seconds and then turn off, as mentioned in my thread. After I got everything cleaned out(cylinders, injectors and fuel tank), I noticed the rpm needle would flutter like yours when at idle or when coating off the gas. I don't really feel any extra shakes or jerks with the needle movement. Maybe my car has always been like this and I just noticed after the event since I was extra attentive? I could have sworn that I read about someone else noticing their rpm's fluttering and other members saying that it was normal.

I hope you can find out the cause or if its normal.

 

This is the thread I was talking about: https://mbworld.org/forums/c-class-w...pm-needle.html

 

Hi,

Recently, I have bought a C200 CDI 2004 with 140000 km millage. I have exactly the same issue as you wrote. Also, I realized the fluctuation during driving is increased when the engine get warmer...!!!

Tomorrow I have an appointment to do a check up. Let's see what they say. If I had something new I will update you. Anyhow, I am searching to find out a solution for it...!

 

Could be the torque converter. Its pretty common for benzs apparently.

 

Yesterday, I had an appointment for check up, and my mechanic had a test drive. Before test drive I filled my tank from another Diesel company and the fluctuations in rpm got less but still I can feel it!

After test drive my mechanic suggest that drive with high power and they told me at that speed and power (1500-1700 rpm) that we feel this fluctuations, the turbo charger get on and off because is in the border line of its activation. He said there is no malfunction code or situation that we can find out. He put some cleaner in the tank and that's all!

But I still believe there is a problem with sensors. Like MAF, EGR valve sensor, etc.

Anybody have any idea about EGR valve sensor and how we can clean it?

 

I had the same issue and just had my torque converter replaced on my w204 m271 engine and now runs great.

 

I'm telling you guys, most of the time with this rpm fluctuation under light/constant throttle problem, it's the torque converter. Mine does the same thing but it's not noticeable unless I look at the tach. When it gets noticeable I will either trade in the car or replace the torque converter

 

I had that problem when idling, and also when moving at idle speeds (moving without foot on pedal). When it was warmer, car would shake noticeably. Took it to dealer and it was a compression leak in one of the cylinders. Turns out the cylinder head was bad and had it replaced under warranty. This was at approx 49k miles. But the problem has occurred since 39k (when I bought the car).
Now I don't feel any shakes, idle is smooth, however..on the highway at constant speed, RPM fluctuates. I don't feel it, but the tach isn't smooth. Maybe torque converter? I don't know.

 

I've noticed that if I don't go into reverse or do anything for a minute, the RPM will go down to around 500 and it will not flutter. But if I immediately go into reverse and drive around, the rpm needle will flutter for the duration of my drive.

How much would it cost to get the torque converter replaced?

Here is a video I took this morning of my cold start, I didn't do anything and just let it sit. It didn't flutter. Sorry if it is short or hard to see.

 

Just took my 2012 C250 to the dealer two weeks ago to have this very issue checked. Service advisor informed me they updated the instrument cluster software, but that it was still gonna do it because the instrument cluster was just picking up RPM signal fluctuation from the engine module. He said there was even a bulletin on this issue the techs consulted and informed me C250s just seem to have come out that way, which I can obviously confirm after browsing on here.

However, the mention of the torque converter above has made me curious. I still have warranty on my vehicle until December. So I want to get any issues sorted out. How would they go about evaluating if the torque converter is faulty? I don't want to take it to the dealer just to have them tell me they can't replace it since it's not blatantly damaged.

I do remember one instance when I had it in drive on an incline with my foot on the brake, and I felt like what I can describe as a slight bucking motion for no more than 3 seconds. It hasn't done it since though.

Any advice would be appreciated!

 

My cdi c220 had the same issue and I've been searching high and low for the answer. I never found it online, and I rarely post things on forums, but I feel like I can help many people out with this simple solution. I'm sure there are other reasons why revs can fluctuate but for my c220 the problem was that I had a vacuum leak through the engine oil dip stick.
THE SOLUTION was a 2 cent rubber O ring around the top of dipstick lol. I hope this helps a few people out.

 

Here is your problem, if your car has more than 100k miles on it, as unusual and as unrelated of a fix as this is going to actually sound, please believe me when I tell you this because i guarantee your not going to naturally be able to logically relate the rpm fluctuation and changing your transmission fluid .. Im not kidding Change your transmission fluid and your problems will instantly disappear with your rpm fluctuation. NOTE THIS though, You will need to change your transmission fluid every 35k-50k miles from that point on. You will know when it is time to change it because the fluctuation will come back!

The reason you don't notice the fluctuation until 20-30min after you have ran your car because it takes that long for your transmission to reach operating temperature..

Believe me, I know exactly how unrelated these two problems may seem to sound to be! I guarantee that this is your problem so much, that Id be willing to pay for your service costs if it does not fix your problem. Although when it does fix your problem, Please confirm this to the rest of the world that will also be quite skeptical in believing a rpm fluctuation is caused by dirty transmission fluid!

 

you ever figure this out? I have the same issue