sikander3786

Hi everybody!

I am so glad to have found these forums as I am already pretty much fed up and exhausted in finding a solution to my problem.

Recently I bought 2006 model C180 Sedan. I have no previous experience with any German cars as I have always owned Japanese cars in the past.

The problem with my C180 is that whenever the RPM is in between 1100-1400, the car starts to jerk, sometimes it jerks just once, at other times 3-4 times and as soon as the RPM goes above 1500, jerking stops.

Most importantly, the car jerks because it suddenly loses 200-300 RPM on the engine. I have uploaded a video to youtube, if you have 90 sec of spare time pls take a look here:


What I have noticed:

1. Engine temperature (cold or warm) has no effect, jerks persist in both conditions
2. Accelerating or decelerating, whenever the engine is in the said RPM range, jerks can be felt
3. Problem persists in both auto and manual driving modes
4. Even if driving in 1st gear, the car keeps jerking in the said RPM range. So I am pretty sure that jerks are not caused by gear shifting

What the mechanic has already tried:

1. Service of throttle body
2. Replacement of all three foundations
3. Replacement of transmission valve body

But the problem doesn't go away. These drive jerks are making me look silly and funny whenever I am stuck in traffic or a signal, LOL.

Please let me know if you need any further details. Thanks a lot for your time.

DjaKRAbb

Hello, have you tried turning "dyno mode" (in a hidden menu) AND esp off? does it still happen in S mode (C starts at 2nd gear)? Do the jerks happen when you are reversing? Did you have any error codes?

What about when in neutral and not driving?

sikander3786

Thanks for the reply.

It happens in both C and S modes, I have tried both.

I have not noticed jerks while reversing. I will reconfirm it soon.

No error codes at all.

I'll try turning off ESP mode and Dyno Mode off as well. Not tried before.

When the car is netrual or in "D" but not driving, there are no jerks at all.

DjaKRAbb

Just an FYI im not very experienced. Ok so in neutral no jerks (so theres no vacuum leak or mass air flow / camshaft sensor problem)

The reason i say no dyno mode/esp is just to rule one more thing out (and it kicks in over 15 or 10 km/h if i remember)

But lets be honest, its probably something in the transmission. Those motor/actuator things? can be removed and tested with multimeter (ive seen people needing to repair them) they sit on the conductor plate (which can also go bad) is that what your mechanic changed?

My knowledge of transmission issues isnt good enough to diagnose this jerk at those revs, hopefully someone else can

*when did this problem start and how many miles/km's on the car?

sikander3786

Yes, that's actually a good idea. I'll get it confirmed in an hour or so as my shift ends.

If it was transmission, shouldn't the jerks appear at randome RPMs at any time rather than at low RPM? The mechanic also wants to replace the Transmission now as he has replace the valve body (probably the conductor plate as you say).

Problem started a couple of weeks ago. This car has been driven 90000 miles.

DjaKRAbb

You make a good point. i dont know exactly how the transmission works so that was just my 'opinion' sorry.
Do you want to pay for a new transmission? more money? or can you sell it with this 'problem'? That seems like alot of money

Have a nice day and goodluck!

*just be sure its 'dyno mode' in the 'hidden' menu, on my model i turn the key one click? and press the reset button 3x and i hear a beep (if i remember) then it worked

sikander3786

Thanks for following the thread. I am also waiting for input from other members.

Yes, just tested with 'dyno mode' off. When I turned it off the notification meter said " ESP, ABS inoperative" so I guess I did it right. But even then, the car kept jerking as ususal.

As you rightly said, I will not be able to sell this car in its current position. I might go for Transmission replacement but I have to be sure that it will resolve the problem.

Till now I am not sure if it is actually tranmission problem or not.

Do you think it can be related to current/electric components? Coils, plugs or something else?

sikander3786

I have just checked the price and transmission is available @ USD 300-350. I think that't a fair price for the part, right?

But again, somehow we must be sure that transmission replacement will solve the issue.

DjaKRAbb

Indeed, need to be sure of the problem. I did find someone else with the same issue here m h h auto.com https://*******.com/Thread-722-6-jer...verter-applied

Does your problem happen only when you are accelerating 'gently'? e,g if you hold brake, bring rpm to over 1500~(above where the 'problem' happens) and release brake (with dyno mode / esp off) in a safe big area incase your wheels spin. Better method = "Try on upphill and keep gaspedal steady at one point. Do car jerk? If it does replace tourque converter."

Doesnt happen in reverse?

^ look.. it could be - t orque converter, oil on the 'tcu' or just a damaged transmission ,,, so if you replace the whole transmission. it could still be the 'TCU' with oil on.. so i guess you should double check theres no oil on TCU (apparently its in the passenger footwell.. im not sure about your model)

sikander3786

Will try the uphill drive on my way back home. Couldn't try the reverse drive as couldn't find that much space to drive reverse here at workplace but will try tomorrow morning.

As you have mentioned now I remember that the mechanic did indeed check the TCU. It is located exactly in the passenger footwell. The TCU was clean just like brand new. I saw it myself.

Where is the Torque converter located? In the Transmission unit or somewhere else?

DjaKRAbb

The converter is part of the transmission, looks like a big round donut , its the purple thing in this video :

sikander3786

Right, so it is part of the Tranmission and will be replaced if we get the Transmission replaced.

DjaKRAbb

You would have to confirm that, incase they re-use your old converter which could also have a problem . you never know. Do the converter test first, the uphill test

sikander3786

I tested my car uphill, 40-50 degree inclination for 2 km, last night. No extra jerks except the one's that I am facing already. Drive was smooth once I crossed the 1600 rpm barrier.

Russell Ormerod

Have you checked intake for leaks? Looked at self adaption values. Checked valve timing. Forget about dyno mode BS! Find a merc technician that knows what to check because you guys really have no clue what you doing!

DjaKRAbb

Haha i agree, im trying my best but you mention 'valve timing'. he said it does not happen in neutral so would that mean the engine isnt the problem? neither is intake/vacuum leaks if its not happening in neutral?

"Forget about dyno mode BS!" - i have to disagree. I did not know this existed. I had my 2 rear wheels jacked up and i wanted to test my hand brake adjustment / brake pipe bleed. The wheels spin and then suddenly jerking and juddering.. which feels like its coming from the transmission. but it was actually the electric brake system freaking out because it thinks i have front wheel lock up. so a simple 'disable' of this to remove any guesses is a good method to diagnose .. remove something else? it turns on around 10-15km'h which is almost in the rpm range the problem occurs. so saying 'BS' is not fair.

Russell Ormerod

Mate please, I have worked on mercs daily for 30 years and w203 since they were launched. Never have I needed to switch off esp to diagnose anything. Putting a car in neutral and saying then it can't be the engine is total nonsense! Where do you get your information from? You are totally misleading

sikander3786

Please keep in mind I am not a technician. I am the owner of that car who wants to get it fixed and I am getting hints/help from whereever possible.

Glad to know about your expertise but I was unable to find any tech of your level here in my city. So, your input really matter for me.

My tech wants to replace the transmission. He is pretty confident that the problem isn't in the engine. Most of the threads I have seen here with similar symptoms, their issue was resolved after replacement of solenoid or valve body. You might be able to better guide me on that.

Another fact that my tech has replaced 3 valve bodies and the issue seems to go away for 10-20 km of drive. Next morning when I take the car out of garage, the jerks come back. That's is something strange but it also probably points toward the problem being with valve body/tranmission, right?

DjaKRAbb

Then you are exactly the person who's input is greatly appreciated and i thank you for that. I am learning myself and asking questions, maybe you mistook my questions as statements (i was explaining my reasons for believing what i think) and i would gladly like to be told if im wrong. im explaining why i have formed an opinion on something and im open to be corrected. putting a car in neutral and increasing the revs = engine working pulling in air / fuel so in my mind if the problem isnt happening here.. but only when he's in drive.. to me that is 1+1=2 or?

Dyno mode / esp - kicks in around 10-15km/h - i read it in my owners manual. and have experienced the juddering effect of it. Why get so offensive or discredit it as a cause (even if its a small % of being faulty) when its simply pressing a button 3 times to turn it off? Scotty kilmer has worked on cars for over 52 years ! "total nonsense" "totally misleading" "BS"

sikander3786

So, transmission was replaced on Saturday. Including the Torque Converter. But the jerk problem didn't go away. The car still jerks same like it used to jerk with the old transmission.

Another thing I've noticed that the car jerks more when the engine is cold. This I didn't notice earlier but yesterday morning and today morning it was quite obvious that the car jerked more frequently and violently when the engine was cold and seemed to settle down after 15-20 min of driving after the temperature crossed 80 degrees.

sikander3786

Just asking, if it was an electrical problem, should it show up on the scanner or show a check light in the meter?

Russell Ormerod

Like I said. Find someone with star Diagnose do a short test and post the results here. Not some cheap aftermarket scanner! Then get comms with engine and post all self adaption mixture values. Also look in menu "check idle speed" i want to see intake and exhaust cam values at idle when hot. Post it all here. Then we can start seeing what's really wrong without guessing. Good luck!

sikander3786

Thank you bro. Let me find someone with start Diagnose first. I'll then post all the results here.

sikander3786

Launch scanner is available easily. Will those reports work for you?

Russell Ormerod

Nope. Only Star Diagnose for proper diagnostics