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Power loss/drop of manifold intake pressure on my smart fortwo CDI 2011

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  • Power loss/drop of manifold intake pressure on my smart fortwo CDI 2011

    Dear members I tried already quite some thing to solve the problem but it is becoming worse, first problem was solved mostly after one restart but this morning this didn't help anymore. Please see attached document for the steps already taken and more details about the problem. Hopefully someone can help me.
    Attached Files

  • #2
    Hi there, I've just read your report and have a question regarding waste gate position with engine running and engine off.

    Above image shows an OM660 engine for the 451 Smart. Unsure if this is the 54 HP or the 45 HP engine. Waste gate actuator appears to be operated by pressure in inlet ducting after turbo, hence by boost pressure. Is yours the same?
    By the way, the hand crank feature ought to be particularly useful. Just keep cranking and off you go.


    • #3
      Waste gate should remain closed regardless whether engine is idling or turned off if waste gate is arranged like seen in photo above.


      • #4
        Hi Tolsen thanks for your reaction and the nice open engine picture.
        Yes I think mine is the same.
        So you say also when starting the engine waste gate should remain closed so to the right see attached picture waste gate open & close.
        I also attached another picture of this morning drop of pressure. After restarting pressure drops and power is lost.
        Because after starting engine again pressure is increasing but at a certain moment drops I think is something electronically (sensor) because if it would be a broken tube pressure increase after restart would also not be possible what do you think?
        Attached Files


        • #5
          I think you have open and close mixed up. Pressure in waste gate actuator moves rod to the right opening waste gate valve.

          Photo shows the KKK KP31 turbo in my 2002 Smart 450 Cabrio. I believe your turbo is same although the short casting mating up with exhaust is different.
          Waste gate actuator contains an internal spring. This spring is preloaded (provided the two nuts on rod are correctly adjusted) and keeps waste gate valve in close position until boost pressure becomes high enough to open waste gate.
          It looks like you have too little preload on your waste gate. This is judging by position of the two nuts comparing mine with yours.


          • #6
            When my car is switched of the lever is moved to the right. I can push manually to the left and than I feel the spring tension. So the spring is pushing to the right. And because you said that waste gate is closed when car is switched of I tought that to the right was the closed position.


            • #7
              So to adjust the preload I was thinking like in attached drawing.
              Do you have any experience with adjusting a preload?
              Attached Files


              • #8
                I adjust nuts near too setting seen in my previous photo. Play it safe and apply slightly less preload. Then connect diagnostics to read off inlet manifold pressure whilst driving flat out up a long hill. Adjust as required leaving a wee margin against suffering annoying over boost and resulting limp mode.


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