Got an issue, please steer me in the correct direction

[IFFY100]

Some advice would be great on the issue below.

What happened
Some weeks ago the car (2010 om642 350cdi) started to hesitate and then after a short while went into limp mode and set the emissions light on. Did a brief scan of the ecu and came back with a p0299. After restarting the vehicle, car came out of limp mode. Some time after coming out of limp mode, the emissions light went off.

Symptoms
Bit of irregular vibration sometimes and after having driven the car for a while, the vehicle hesitates/delays acceleration when pushing the accelerator. I've noticed that if placing the vehicle into wide open throttle, it will drop 2 gears to try get the power in. I did also notice that when limp mode was activated, the vehicle sounded as if it was heavily sucking air when idle and pushing the accelerator. This never ever did happen.

Plan of action

1. Visually inspect air hoses
2. Smoke test air connections
3. Somehow test turbo actuator (please advise how, as the fault now is a hesitation or sometimes limp mode (not often))
4. Get codes read. Leaving this till last because I will need to get an appointment with a specialist and all other things can be done immediately

Is there anything anyone can add to help me in the process of finding this fault?

 

[PolishGeorge85]

Some advice would be great on the issue below.

What happened
Some weeks ago the car (2010 om642 350cdi) started to hesitate and then after a short while went into limp mode and set the emissions light on. Did a brief scan of the ecu and came back with a p0299. After restarting the vehicle, car came out of limp mode. Some time after coming out of limp mode, the emissions light went off.

Symptoms
Bit of irregular vibration sometimes and after having driven the car for a while, the vehicle hesitates/delays acceleration when pushing the accelerator. I've noticed that if placing the vehicle into wide open throttle, it will drop 2 gears to try get the power in. I did also notice that when limp mode was activated, the vehicle sounded as if it was heavily sucking air when idle and pushing the accelerator. This never ever did happen.

Plan of action

1. Visually inspect air hoses
2. Smoke test air connections
3. Somehow test turbo actuator (please advise how, as the fault now is a hesitation or sometimes limp mode (not often))
4. Get codes read. Leaving this till last because I will need to get an appointment with a specialist and all other things can be done immediately

Is there anything anyone can add to help me in the process of finding this fault?

So, it may not be best way but it works.... Just follow this video.... thanks to that I have managed to argue with my local "cowboys" not to replace turbo.

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There is a lot of reasons why your car is behaving that way. On my e350 for example,was injector 6 fuel return pipe not been correctly connected.

I would recommend diagnose/code read first.

 

[Riva811]

check your DPF and also the sensor

 

[Koplint]

It seems like you're on the right track with your diagnostic plan. Here are some additional steps and considerations that might help you further in diagnosing the issue:

1. Check Intercooler Hoses and Connections: Ensure all hoses connected to the intercooler are intact and properly secured. Any leaks or loose connections could lead to irregular airflow and affect turbo performance.

2. Inspect Turbocharger and Actuator: You can manually check the turbo actuator's movement by carefully applying vacuum to it using a hand vacuum pump. Verify if it responds smoothly and consistently. Any sticking or erratic movement might indicate an issue with the actuator.

3. Boost Pressure Sensor Inspection: Check the boost pressure sensor. It's responsible for sending data to the ECU about the pressure in the intake manifold. A faulty sensor can cause incorrect readings and trigger the P0299 code.

4. Exhaust Gas Recirculation (EGR) System Check: Issues with the EGR system can cause similar symptoms. Inspect the EGR valve and associated components for carbon buildup, clogging, or malfunction.

5. Scan for Codes:** While it's on your list, scanning for codes can give you a more precise starting point. Sometimes, there might be pending codes or other diagnostic trouble codes that can provide additional clues.

6. Consider Professional Diagnostic Tools: If you have access to or can borrow more advanced diagnostic tools, you might be able to perform more in-depth tests, such as live data monitoring while driving to pinpoint issues occurring during specific driving conditions.

Remember to approach each step methodically, starting with the easier and more visible checks before moving onto more complex diagnostics. If you encounter any specific error codes during the scan, they can significantly narrow down the possible causes. And if you're uncertain about any steps, consulting with a specialist or a mechanic experienced with Mercedes-Benz vehicles can be immensely helpful.