Hi all.
2013 W212 with the M271 EVO.
Currently at 76,000 miles.
Only just changed the timing chain kit last week as the tensioner was failing - the dreaded start up chain slap.

However, a few months prior to this, the car had this “hesitation to proceed”, when accelerating - like a series of very light jerks.
Also, at traffic crawl speed, the RPM fluctuates slightly, producing the same light “wave” or jerkiness.
I have scanned it every time and nothing comes up.

Now, and this has happened twice, whilst accelerating lightly, the car feels like the ignition has been cut off for a half second, and starts again - like what happens at a stop light with Eco on.
a few dashboard lights come on (too quick to notice) and then extinguish. Except the Eco button which comes on.

Again, nothing on the scanner.
Scratching my head here.

 

Which good scanner is showing you no fault after the dash lights flash up ... scarry driving.

If chassis really doesn't report any faults... you're gonna need to go fetch live data!

Based on your inputs, the top of the list is to read fuel rail pressure... still low mileage for normal fuel filter expiration.


Let's get one thing out of the way...
where did you purchase the maintenance parts:
likely copies or trusted genuine??
A fake timing chain tensioner can be 100% responsible for misfires.

 

Hi.
Thank you.
The scanners I have used are
Launch X-431 PRO 3
Launch X431 Creader Elite 2.0 BBA

the usual suspects come up - blower vent motors, position sensors, lights, seats, etc. but nothing to do with engine or electrics. I too find this really strange.

No. They were not MB OEM parts, but Febi OEM replacement.

The fuel rail pressure makes a lot of sense.
Could this be coilpack related? But then the sudden off-on…

 

That scanner has full MB modules coverage. We can trust it for accurate reports.

You confirm using OE parts by Febi.

Fuel pressure unknown... vs. poor ignition: Lets read Long-term Trims: LTFT 1+2 ??
This will tell us the answer.

How long ago did you replace your long chain single tensioner: recently or 500Mi ago?

 

I will have to do a live data read for that.

the full tensioner kit (cam wheels, tensioner, rails, crank wheel, chain) was replaced about 2 days ago.

 

M271.8xx EVO is your engine. 1.8L Turbocharged.
Its SIM 271 ECM made by Siemens is not too robust.
My friend's W204 of 2010 same engine, had issue with the ECM ignition driver, ended up needing new ECM.
But DTC exist, as the condition worsen.........misfire and low power. Cant even start the engine sometimes.

This M271.8 EVO engine still uses oldie 3 wire ( 2 wire actually ) COP Ignition, where the electrical load ( using driver ) is handled inside the SIM 271 ECM and
not smart COP with its on power/driver pack built into the coil like M276 or M278 or M157, where then the ECM MED177 has light duty only sending trigger signal to the 5 wire COP.

Read here on my friend M271.8 engine and see what you can learn from it.........
https://mbworld.org/forums/e-class-w...c250-w204.html


Good luck......

 

ONLY TWO DAYS AGO...
I'd give the engine computer time to re-learn the new engine TIMINGS after this essential repair.

Before repairs the chain was not tight enough and timings were poor. ECU learned to match loose timings with detuned performance.


Now throttle response should get more precise little by little. Enjoy.

 

I wouldn’t know where to begin. This was some MENSA level, super genius kind of content. It was definitely way above my meagre capacity of comprehension.
Thank you very much for directing me to the post.
What I got from that is “your ECU is on its way home. Good luck” LOL!!
I pray that’s not it.

CaliBenz says give it a few days, I’ll begin there…for now…

 

So, I have this “Big Brother” S550 and it does this sometimes scary engine bog-down.

It happens when I make a very sharp fast turns. Particularly this happens when leaving my sub division where I have to stop at sign. Then when I take off with my heavy foot on the pedal and make the 90 degrees right turn it does it almost every time. This has taught me to make this turn slower.

What I think the problem is that the car leans too much and allows the right rear wheel the slip under lots of power this car puts on road and the slip control takes action. I have seen a blink of something in the dash but it is so fast I cannot tell what it is. But, I think it is the slip control warning light.

I have scanned the car with Xentry and there is no codes, which slip control does not leave as it is not an error for it to work when needed.

But, you say you have a problem under very low load so it is not slipping for sure, but could it be a problem with a wheel speed sensor that has not failed (no codes) but gives wrong speed info for the slip control to come on?

 

WELL!
Last night, she cut out 4 times.
Much jerkiness, dash lights all on, RPM swinging from 0-4 and then cutting out.
Wanted to set it on fire
Put the AC off and all was well...WTF
Took her to the shop (which I requested be opened due to the "emergency")
The Launch pulled pages of Red - ECM/TCU/etc/etc.
HOWEVER...after prodding about to see what's what, the turbo outlet pipe has a large tear in it!
The mechs think it's because of huge boost loss, the ECM is misbehaving with fuel trims (CaliBenz & Surya ) due to intake issues and then calling it a day and cutting out (the TCU had lots of CAN BUS errors due to the cutting out. They were cleared off)
Will update this evening...the cheapest MB you buy is the most expensive MB you buy!
Truer words ne'er spoken! PITA

 

If your engine cuts off dead while driving it's a dangerous emergency to keep your Mercedes off public roads.

No1 culprit could be the low voltage "drained by driving" below 12 or 11Volts.
Read chassis voltage below 12.3V = trouble!!


No2 culprit could be low fuel delivery cutting out. Read fuel rail pressure

Run a compatible OBDII scanner to help diagnose this.

 

M271.8 uses air to air aftercooler.
Quite oily air , due to often bad performing breather system which among others is the plastic cylinder head cover as part of the PCV system.

The rubber boost hose has unique seal on each of its hose METAL end, it does not use hose clamp but a locking clip shaped like a U ring, hence it has o-ring as metal to metal/plastic sealing.

Attached the tech doc on M271.8 EVO, where owner can learn of his engine.


Turbo charged air output RUBBER hose #1, before going to aftercooler. See the metal oil hose end.


.




The above hose, its other hose end, into aftercooler



The special clip I mentioned.
The metal hose end has internal o-ring seal, which can also leak.


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.






The 2nd hose, aftercooler output to intake manifold. This is the hose end at the intake manifold throttle body adapter



Throttle body seen from its plastic adapter




============


Your plastic engine oil filter +oil cooler housing combo if it never yet fail, it will fail guaranteed. Sad, I know, but it is what it is.


.


..





The turbo charger oil seal (2) and coolant seal 2), will leak too




This coolant plastic hose,will break too. Plastic with age & vibration = brittle. 10 years is good enough already. This W204 plastic pipe 13-14 years old when broken, very fair.


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.




=================

Soon your PCV system will need love too.
I wont post more photos, I do not want you to loose sleep.


Good luck maintaining your aging car, its always a challenge for us when many parts uses plastic and o-ring seals.
My W212 E400 is aging too........

 

Thank you for the immense treasure trove of information!!

…it’s the ECU…

 

Dang 2013 to today 2026 = 13 years.
I believe your climate is not as hot as Jakarta-Indonesia average all year round and with less super bad traffic jam.

My friend's M271.8 ECM.
Year 2010 car, ECM kapoot in Dec 2021. 11 years at best.

In fact M272 engine's ME9.7 Bosch ECM does not live long too in my country. Typical 10 years is common failure time.
Usually there are capacitors which leak its liquid and cause short circuit.

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How did the techy define it is your M271.8 engine ECU/ECM being the problem ?
Was it the COP driver too ?

 

After your ECM prognosis, I asked the mech.
He reminded me that we had tried to fit an aftermarket push to start system and we ran into the same COP 2 vs 3 wire issue.
So he said this may actually be something.
The pins were all spotless, and the ECU did not throw any codes via OBDII.
When he took it out, he said there was an "Internal control module runtime error and and an engine off timer(?) implausible value..."