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Hello to all

I am currently troubleshooting my friend's E200 sedan, automatic gearbox (651 engine).

The timing chain broke almost two years ago. There was damage to various parts. The engine was completely rebuild in the MB service center.

Since then the car started to act a bit funny. Lack of power when overtaking and such things. They did never accept any responsibility. First they though (me too) that after the engine rebuild a limited power ECU remap was done but later dismissed it and told that the ECU was not touched. As time went by the car started acting even more weird. When you press the throttle pedal there is some lag before it catches the revs. It doesn't rev that quickly as it did before but if you wait a bit it will rev close to the red line. When you drive it same story. It is very hesitant. Not "quick". Can't do overtakes. Sport mode almost doesn't do any effect. Sometimes it just falls in limp mode with no check engine light on during normal driving. Fuel efficiency went down. It is now around 8-9L/100km, before it was about 5.5-7L/100km. When you let it rev up while driving the turbo makes boost, it revs near the red line but it does not go fast as it should. It is more like you are having some heavy cargo in the trunk. The engine revs loud but the car does not produce much speed.

There are several error codes in the ecu. P2263, P2541, P0105, P0103, P0107, P0113, P0133, P0045, MAP, MAF, O2, pressure sensor of low pressure fuel system (not sure if it is the one in the fuel tank), turbo pressure under standard values, today it has shown even the accelerator pedal position sensor error (this could be the reason for the delayed response). Through Torque and some bluetooth adapter I could test the MAP, MAF, and think they are working very well. Today I replaced the O2 sensor thinking that may solve the problem but the errors remained. From the checks I did it seems the O2 does not give any reading or even more probable the ECU does not really use or engage the sensor. Before replacing I was able to read 0.4 volts briefly and that was all. Doesn't matter warmed up or cold. Always the same. That is why I was pretty confident it could be the O2 sensor (didn't exclude other things too). In the meantime we took apart also the electronic turbo actuator and tested it and it seems that it is working very well. That was also a tip from some other guy to check and obviously it did make sense because of the turbo boost error code. While driving and checking the Torque app the turbo boost reads around 17.5 psi at around 4k rpm. Which seems more than enough, not sub value like the trouble code shows. We went to a guy that worked for MB for some 20 years and specializes in diagnostics and electronics. He measured and focused a lot on the DPF. The car has some 200k miles so it was possible. He told us he is very confident that the DPF is working flawlessly but didn't know the solution. I did inspect the turbo for bearing play and it seems the turbo is in very good condition. I didn't notice any leaks or damage in the intake. The fuel injectors where inspected some time ago and are fine.

I am kindly asking for your ideas and directions. Maybe someone of you (professional or not) had a similar experience.

Thank you very much in advance!
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