QuestionCiao Robert, MB 220CDI 2000 - 143HP. Sometimes, perhaps each 100km it happens that the engine halts at around 3000 rpm - 2800,3100 - never at exaclty the same rpm; when pressing the accelarator nothings happens; the engine gives only a fraction of its HP. When switching of the engine about 10seconds (while freerolling) and then starting again the engine performs well again until the next time it gets hung up. I think that it has something to do with the air intake, something closes the air intake and strangles the engine, some electronic malfunctiion which closes the intake by mistake??!! The car is wonderful but this fault is irritating!! Thank you for your help! Best regards (from Rome Italy)
AnswerI am going to offer some general info and then suggest trial and error testing going from least to most expensive.
Is the pause abrupt or gradual. When it returns is it instant on or gradual.
Example: Fuel exhaustion... when an auto running out of fuel the injector are pumping fuel, but the lack there of cause a gradual drop in rpm until the fuel is exhausted.
Example: Air restriction... because a diesel has no ignition the engine air is stopped abruptly thus stopping the combustion and turning of the engine.
If the engine stops abruptly as if the key were turned to off, you probably have an electrical or mechanical issue with the MAS air flow sensor or its equivalent.
Anything that interrupts this electrical message to intake system could cause this problem.
Even a bad ignition switch could cause this problem. At speed in an area of no traffic, just reach up and shake the switch. If you problem returns there is your fix.
Here are some additional thoughts.
This auto probably uses the computer to manage speed input from the fuel pedal position to talk to the intake air flow sensor, which in turn talks back to the computer to tell the injectors how rapidly to add fuel.
In addition, there may be relays to the fuel pump which controls the fuel rail pressure.
I would check the fuse panel.You will need the manual to see which fuses are involved with the fuel system or intake system. If this car uses the typical ceramic with copper or aluminum strap they are notorious for getting high resistance at the points. Polishing not only the bullet end of the fuse but the sockets of the holder will often solve many problems. When in doubt purchase new copper fuses of the same amperage and install after cleaning the sockets. 'The least expensive fix.'
If there are relays related to these circuits, I would pull the relays and clean the pins. Wiggle them during reinsertion. Again corrosion can cause electrical faults.
Next, I would suspect the Mass Air Flow sensor or its' equivalent. I know of no fix, so you may need a dealer to check it out.
If you know of someone with a computer code checker, you should have them run the check and it may come up with some clues to your problem.
Good luck and let me know if I have help with your problem.
Robert
