W164 OM642 Starts Shaking at Over 3500 RPM

[Mercedesman]

The engine runs fine at idle, but when I rev it above 3500 RPM, the engine starts to shake violently and sometimes even stalls. Sometimes it even goes into emergency mode and smoke comes out of the exhaust pipe.
All 6 injectors have been tested and are working fine, the fuel rail pressure regulator is new, the fuel pump pressure regulator is new, the PCV valve is new.
I stop and start the engine again, it runs perfectly again.
No fault codes were found during the scan.

Has anyone had this problem? What should I do/check?

 

[escarolo]

My father in law had a similar problem with his E320 CDI W211 (same OM642 engine) and it was a leak in one of the fuel filter tubes. The filter was replaced by Mercedes-Benz and they broke one of the hoses with a metal clamp.

 

[PeteM123]

I also think it could be related to not enough fuel flow, however if you already have a new pressure regulator for the rail and pump, you might want to check to see if the fuel line is clogged (eg fuel filter, fuel line itself, or fuel pick up point in the gas tank)?
Do you have diagnostic software that can read pressure and flow levels and check they are within specifications?
On the other hand, if there are no fault codes, then it is potentially normal.

Another area could be the air filter and the entire air intake. If you have a leak or blockage, the air/fuel mixture could be incorrect and adjusting it becomes critical when running at higher RPMs.

When you write that after stopping/restarting the engine runs fine, does this mean that it runs at high speeds as well, or only at idle or low speeds?
Is this a diesel engine with DPF?
You can check to see if the DPF is saturated, but this will usually result in a fault code or check engine light.
Not sure if any of the air, fuel flow and DPF pressure or differential pressure sensors are faulty and sending false data causing incorrect operating conditions but not enough to cause a fault.

 

[RicoChef]

Check this out:

1. Fuel pressure under load. Make sure the pump delivers sufficient pressure at high engine speeds.
2. Mass air flow sensor (MAF). Clean it or check if it gives correct values.
3. Ignition system. Check spark plugs, ignition coils and cables under load.
4. Exhaust system. Check the catalytic converter for blockages.
5. Crankshaft/camshaft sensor. Test signals.
6. Vacuum leaks. Check all hoses and connections.

With the help of these points you will be able to find the cause.

 

[Mersovod]

Check the pressure fluctuations in the ramp and the stability of the pressure in the low circuit. Was the pressure regulator in the ramp changed separately or together with the ramp? If separately, then there may be a microcrack, a violation of the tightness, and, accordingly, leaks inside the ramp.

 

[escarolo]

Replacing a fuel pressure sensor is inexpensive, but it could be the cause of the problem.

 

[Mersovod]

Replacing a fuel pressure sensor is inexpensive, but it could be the cause of the problem.

The pressure sensor fails very rarely, and Xentry always indicates its malfunction.

 

[Mersovod]

Check the B60 sensor readings. It may be heavily clogged with soot.

 

[gltcls8]

What is the fuel pump pressure?