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  1. #1
    william10cam's Avatar
    Join Date
    Apr 2012
    Roseville, MI

    2004 Msx 150 only goes 45 and has rough idle

    Hi, I'm new to PWC's I just got my first pair last week and already having a problem with one.

    My msx 150 does not want to go any faster than about 45mph and the idle seems to jump around from about 1500-3000. When you start it up on the trailer it sounds like it wants to just take off right away.

    After reading a few other threads on this site I have tried a few things but have had no luck yet. I changed both spark plugs, cleaned both map sensors which had a good amount of oil on them, and check the wastegate by removing the screw that attaches to the arm and that moves freely.

    Some things to note, I don't know how old the oil and fuel are, it could be from last summer, when taking out the small black tube to get to the bottom map sensor I did notice a small amount of milky white oil in there as if the oil was overfilled and got water in it. The oil when being ran for about 30 seconds shows barely below the overfill mark.

    Any advise would be HUGELY appreciated. Thanks!!!!

  2. #2

    Join Date
    Jul 2007
    Vermillion SD
    Be careful, very careful with oil levels. Read the introductory materials on the MSX 4 cycles on this site. It could be an oil contaminated intake circuit including the intercooler, pull the hoses and have a look.... you may have to clean the entire circuit.

  3. #3
    Kosh's Avatar
    Join Date
    Sep 2007
    If your map sensors had oil on them, treat them as unusable and replace both. Sorry for the bad news dont try and run it with these as it will eventually confuse the ECU to the point requiring a reflash.
    I see a recent post on MAP sensors at a reasonable price.

  4. #4

    Join Date
    Apr 2010
    Stamford CT
    If you have not seen this thread: it maybe useful.

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