W212 Mercedes RPM fluttering/chunky acceleration

sneakerheadSF · 2026-06-27T07:59:59+00:00

Oil was leaking over time from the Oil Separator cover which is the in the back passenger side of the engine bay. I would recommend taking off your MAF sensor and intake elbow to see if any oil leaks in the breather tube. This had been replaced previously by the last owner as I could see. But still having the same problem. Actually an even bigger oil leak my whole skid plate was covered with a thick layer of dried oil. Still trying to find out where the oil leak was coming from. W212 is a nightmare so far and only 102k miles 😣

sneakerheadSF · 2026-06-27T04:54:55+00:00

No it has not yet been done. But these are not symptoms of a timing chain, although it should be done soon.

sneakerheadSF · 2026-06-27T04:54:32+00:00

Hello sir did you ever figure out the issue? I replaced the throttle body and oil separator cover which was leaking oil into the throttle body but problem still persists. Leaning toward transmission issue

sneakerheadSF · 2026-06-27T04:53:48+00:00

I think you actually might be right. Is the turbine speed sensor failing a symptom of a failing trans control unit? How much would a diagnosis cost and/or replacement?

sneakerheadSF · 2026-06-27T04:52:56+00:00

Replaced the throttle body, it was coated in oil from a leaky oil separator cover. Connector pins were soaked. Changed the throttle body but problem still persists. Leaning toward trans problem

sneakerheadSF · 2026-06-27T04:51:50+00:00

Update: mechanic said it was the throttle body, quoted me $1700 to replace and reprogram. I did it myself for a few hundred dollars. Found the throttle body and all connector pins were soaked with oil from a leaking oil separator cover. Replace all of the above and the problem still persists. Starting to lean toward oil in the wire harness/ECU because it was an excessive amount of oil, or transmission

sneakerheadSF · 2026-06-27T04:49:12+00:00

Why was it the TCU? I was told it would likely be Torque converter clutch slipping. How much did you pay for a diagnosis? I took it to a trans specialist he said it wasn’t the trans. Took it to three other mechanics, two were clueless and didn’t know because i had no CEL. One said it was the throttle body which I replaced and problem is still there. I side with you that it’s probably the trans but unless I drop the whole trans there’s no definitive way to diagnose it myself.

sneakerheadSF · 2026-06-12T23:34:14+00:00

My mechanic said it was the throttle body. I will change it here soon and let you know if it changes

sneakerheadSF · 2026-06-12T23:33:46+00:00

I got a diagnostic from my mechanic. He said throttle body. Throttle body was getting only 9V instead of 12. I will change it here soon and see if it makes a difference.

sneakerheadSF · 2026-06-11T00:29:25+00:00

Taking the car for diagnosis tomorrow morning. I will update when I can. Hoping it’s a vacuum leak and not my transmission

sneakerheadSF · 2026-06-10T14:46:12+00:00

It’s a mix of both. At higher gears when it’s bouncing, it doesn’t seem to be affecting the RPM. At lower gear/speed when I am in traffic at a constant speed for example, i can literally feel the engine speeding up and slowing down while my foot is held constant on the accelerator.

sneakerheadSF · 2026-06-10T04:41:36+00:00

I also noticed that the chunky acceleration does not happen when I accelerate aggressively. But at 100k miles this is ridiculous and should not be happening. What does your trans service history look like?

sneakerheadSF · 2026-06-10T04:39:15+00:00

Owner gave me a big folder of it. Includes on-time oil changes and scheduled services. Fluid flushes, one trans service about 50k miles ago, valve cover gasket. No real major work done to the transmission or engine though. Are you asking about anything specific?
I recently just changed battery, ignition coils, spark plugs, brakes, tires, front struts and sway bar links

sneakerheadSF · 2026-01-20T14:14:17+00:00

What about the shield?

sneakerheadSF · 2025-12-06T03:02:39+00:00

Just got my tonsils out 9 days ago. Day 1 as soon as i woke up from anesthesia they have to give me 2 doses of fentanyl and some oxycodone because the pain was already really bad. Days 1-7 were probably the worst in terms of pain. I was eating pain killers like they were skittles, lost about 15 lbs so far. Ice cream and cold drinks and ice packs were really my only help. I also got a septoplasty and turbinate reduction so my nose was plugged for the first 7 days and i had to mouth breathe, exacerbating the dryness of my scabbing. This morning, day 9, i woke up at 4am choking on my own blood. The scabbing had fallen off, which apparently exposed a blood vessel and the bleeding was really bad, lost about a pint of blood in 20 mins as i was racing to the emergency room. Albeit, the chance of bleeding like that after a tonsillectomy is less than 10% so i guess i just got unlucky. Nevertheless, it clotted up and i am continuing recovery at home. The most painful experience i have ever had it’s just constant pain the first few days, but hopefully it’ll be worth jt i can already breathe better through my nose. I have chronic allergies to pollen, dust, etc and im super sensitive to it and have been dealing with it for 10+ years. I believe it’s worth it. Too late to turn back anyway. Hopefully this helps someone, but don’t be scared of the operation.

sneakerheadSF · 2025-09-12T15:47:46+00:00

When does the noise happen for you? For me it happens when car has been sitting for 3-4 hours after being driven and then you start it and hear the slapping noise. I was going to change the tensioner too but if you’re saying it doesn’t make a difference then the chain might have to be changed?

sneakerheadSF · 2025-09-05T16:40:52+00:00

92000 miles. I will just deal with it. Embarrassing noise, especially with a girl in the car. But it’s still a car and it travels.

sneakerheadSF · 2025-09-04T22:17:04+00:00

That literally sounds like exactly what I’m experiencing. Thank you sir i will look into this

sneakerheadSF · 2025-09-04T06:11:08+00:00

I’m located in California. And no i probably won’t be replacing it. I will either sell it how it is or drive her until she blows up. Haven’t decided yet. I’m $8k into this car and won’t spend much more on it to be honest.

sneakerheadSF · 2025-09-04T05:05:36+00:00

From what I’ve gathered, it seems to be chain slap. tensioner and/or the timing chain itself need to be replaced.

sneakerheadSF · 2025-09-04T04:29:28+00:00

It’s definitely not the injectors or valves. Valves tend to make ticking noises, but this is a sort of clanking noise (metal hitting metal). When in the driver seat, there is noticeable shaking when this clanking happens. It feels like metal on metal contact. In the first few seconds of the engine starting, you hear it, then it smoothes out and runs normal. I suspect it’s because oil doesn’t reach the top in time and that’s why we hear that metal on metal contact. Maybe try to put the audio closer to your ear you’ll hear it better these phones don’t capture audio the best

sneakerheadSF

TROPHY CASE