https://mbworld.org/forums/c-class-w...-question.html

sooo, what next?

ECU tune from eurocharged? high stall torque converter? rocket launcher?

I'm in the same situation where the transmission will jerk after letting off the throttle in 2nd gear, and applying throttle... I assumed this was the normal torque converter jerk that most people get in their C32's.

i dont know...people are so terrible at describing car related stuff. my impression was that most people get the jerk when slowly accelerating from a stop...

maybe there are people in both camps...

did you see my videos i posted of the jerk?

the thing is, its definitely in the software because you can bypass the lockup event at 2000rpm by giving it 50-60% throttle. the rpm's just go right to about 2400 and the car accelerates for a few hundred rpm's and then shifts smoothly into the next gear.

i guess i'll have to take a video to be more clear

anyone else?

I am having the same problem where I go through first and get to second gear in S mode, then let off the gas, then get back on and the car jerks, somewhat looses power, and then gets back on it. I am also experiencing the 1500 rpm jerk in W mode and a slight jerk in the middle of 2 gear in S mode when normal driving. I have had the transmission, tcu, radiator, torque converter and other little things replaced under warranty. I was guessing that that is the nature of the car to be jerky. On second note, I owned a 01 C320 and the ride quality was MUCH better than the C32 and was a MUCH smoother. My c320 never jerked in any way. It was always smooth and power was on tap. The C32 however, gives me nothing but problems. Now I am having slow acceleration issues which I think that my TPS sensor is causing and I have to get a new accelerator pedal. Our issue has probably something to do with the torque converter unlocking because once you let off the gas, it feels like it should unlock because the car is not accelerating any more in second gear, and when you get on it again, it jerks. I am also thinking it is a software issue and nothing serious, but annoying as hell. Please keep us updated, and I hope you solve the problem.

too bad there's only about 2 people out there with the high stall torque converter. one of them says it got rid of it. who knows?

bamp

I have the same problem as you. I get a hard clunk when I'm doing a slow acceleration and I've noticed it even after longer drives.

The car seems to respond normal under heavy acceleration, but I've even had the clunk issue when getting on it hard. The only way I can explain it is that the car will speed up and then seem to decelerate and then catch and continue to speed up. I haven't had it happen a lot, but I've noticed it.

I feel like my transmission holds back my acceleration, but I think that's another thread.

i never get the clunk if get back on the throttle hard, this is because the tcu never tells the converter to lock up under heavy load (normal)

WOW. Funny you should mention, my car acts the same exact way, but almost every day. When I am slowly driving and I give it some gas, it sounds like the converter loads, then slips and gets back on it again slowly. When I push the gas pedal half way to downshift (when driving at a constant speed), the downshift is very slow and sluggish. It sounds like the car stalls, then it searches for a gear, then it gets into some gear and slowly accelerates. I thought it was my ic pump so I put in the cm30 and NGK irridiums, but still exactly the same. I am kinda leaning towards the TPS sensor, and I think that after I change the gas pedal, it will go back to normal. After reading this thread about the failing/sympthoms of a bad TPS sensor, I am 90% sure it will cure my problem.

http://www.mercedesforum.com/forum/s...ad.php?t=36789

Anyone ever try this? I'm not sure if it applies to our issue, but found this vague information in the service DVD...

Good find gt4awd, that process seems very similar to this (Go to post #11 from the thread):

https://mbworld.org/forums/c32-amg-c...-c32-tsbs.html

I took my car to the mercedes dealer and explained my problem and also gave them that info about the torque converter adaptation. They told me that they can do that process, but will take around 2 hours. One service representative told me that it is dangerous for me to get procedures of the internet quote "Be careful what you get off the internet, by the way, how on earth did you get that?" He did not like the idea that people are actually doing research and trying to fix the problems themselves rather than going to the dealership lol. So, I figured 2 hours *$130 per hour would equal $260. For one, I am not quite certain if it will fix the problem, or I will just throw away $260 in this tough economy on a problem that even when "fixed", might still come back to haunt me much like the 1500 rpm jerk that came back after new transmission, radiator, and the torque converter.

i get the jerk at a slow acceleration. not so much when applied 60-100% trottle. from all the other threads this looks as to be the gykol? im not to sure but for everyone else's experiance this seems to be the problem

this sums up what i was trying to say
without the other stuff about the c320 and getting the parts replaced

There is no way that my car has glycol contamination. All my parts that include the transmission, radiator, a torque converter, and a tcu are around 13k old. I am still leaning towards it not being a transmission problem, but rather a TPS problem, and will be ordering a brand new gas pedal assembly from parts.com soon. It could also be an inadequate adaptation of the torque converter to each gear.

perhaps it could also be a speed sensor flaking out, just tossing some ideas out there

Blamestorming here... any chance this has to do with the S/C engagement-disengagement process? Seems that the TC would "see" drastically different torque levels, depending on if the S/C is engaged or not... accellerating might engage the S/C, then backing off throttle and load disengages, TCU/TC gets confused about when to lock up or not, causing some of the jerks/clunks issues reported by owners.

Any merit to the above scenario?

I can feel when the sc clutch engages, and it is a different kind of jerk. Besides, I also have a brand new sc pulley+clutch. Most of the time the car jerks at partial throttle. What it actually does is it leaps forward, jerks and you hear a buzzing sound like a drone, then it tries to catch up to speed. A lot of times, I can hear the supercharger, and as soon as I get off the throttle get back on, I get a jerk. The most annoying one is in 2nd gear,in D, S mode. I accelerate moderately 1st to 2nd gear, then let off the throttle, then back on and the car leaps forward.

What are the symptoms of a speed sensor failing?

just saw your post and vid on the trans. clunk thingy... had the same problem just like your vid but in addition, happened only on one occasion when merging, the car shifted into neutral by itself. so, i recently had a trans fluid flush and filter replacement as well as a trans, software flash and that seemed to solve the problem so far. I have about 45k on the odo. hope this helps and GL.

John

Rough engagement followed by droning or buzzing sound is listed as either glycol contamination, or EGS ECU adaptation problem. Says to have all adaptation codes cleared as a first step, and then perform glycol test if problem is still present.

what's EGS ECU adaptation?

The EGS is also sometimes referred to as the "TCU" and controls transmission functions. It's a box (Siemens, IIRC) in the passenger-side footwell.

Since the TCU "learns" driving behavior and attempts to adapt shift patterns and activity to it, clearing the adaptions wipes out that memory and can potentially fix a misbehaving gearbox. Any reputable shop with Star should be able to clear those adaptions for you, I believe.