My 2010 CLC200 (M271.957 engine) is suffering from a mysterious loss of power – it can hardly drive anymore. During a short drive around the corner, the RPM goes up to just under 4000 before it shifts into the next gear. At first I thought the transmission was malfunctioning, but my highly experienced mechanic immediately determined that the engine was lacking power/torque.

I recorded the following data with my own iCarsoft MBII tool:

MAP – Manifold absolute pressure (pressure in intake)
RPM – Engine speed
VSS – Vehicle speed km/h
MAF – Mass airflow
The intake pressure goes up to 190 kPa! Is that normal?


Signals driving around the block

This time cam adjuster plugs removed

Then I repeated the drive, this time with the camshaft adjuster plug removed.
It was a lot better, but still bad. This time, the pressure only goes up to 167 kPa.

Is there something wrong with the timing chain?
Valve cover off – everything is exactly right (I mean exactly, not just approximately).

My mechanic did the following:
Compression test
Smoke test to check for vacuum leaks
Removed the compressor, everything OK
Switched the air flow meter
Switched the crankshaft sensor
Switched the camshaft sensor
106,000 km 15 years "young"

All without success.

My mechanic is highly experienced, with decades of experience servicing Mercedes, BMW, Porsche, and Ferrari vehicles. He has never had to return a vehicle without being able to repair it.

At the moment, the control electronics are being examined by an Australian specialist company that repairs Mercedes ECUs – in the hope that they will find something.

My mechanic has the original STAR Diagnostic System, which outputs the following:
P200 A – Bank2/5 Hot film mass airflow sensor
P2029 – Mixture Format Self Adaption (Fuel Trim)
P202C – CAM measurement from instrument cluster
P203A – N3/10 ME – SFI control module
P2056 – Y49 exhaust camshaft solenoid.

Additionally: The fuel pump failed, and during the last trip (before being towed), the engine experienced a number of severe load changes (e.g., at 3000 rpm, the fuel suddenly shut off, then back on again).
2 weeks after getting the fuel pump replaced this problem arose.

I hope that maybe someone has had a similar experience with suggestions as to the root cause?

 

After all the failed attempts to diagnose the problem, a conclusion was reached that something deep inside the engine is badly wrong. Examining timing chain after rocker cover removal - looked 100% spot on ok.
A local wrecker happened to have an affordable engine with only 75,000km on offer, and the obvious path forward was to get that one instead of pulling the engine part clocking up more $ for repairs than just replacing it.
In the process, removing the exhaust system had something "loose" within the catalytic converter can.
With hindsight (and after opening the cat can), some item of metal came out of the engine, and trashed the catalytic converter, hence causing a restriction/blockage in the exhaust system.
We still don't know what actually went wrong inside the engine (the exhaust was opened by a specialist exhaust place, they binned the contents so we did not get to see the offending metal bits)
Below a trace of the vehicle driving beautifully again.
Key difference: MAP only rises for a very short moment when accelerating, dropping right back thereafter.


(the reflection conceals MAP=43, but that's just the reading at idle at the end of the graph)

 

Regardless of the provenance of the metal shard, anything metal coming out of an exhaust port qualifies as catastrophic failure. Glad you have found a suitable solution.