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  1. #1

    Just acquired MSX 150. Starts and idles. CEL flashes. 1500 RPM limp mode.

    I just bought a 2004 MSX 150 with 30 hours. (It came as a package deal with an Aquatrax I wanted. It was a a repo sale, so I have no details about its history. It has been in storage for at least three years.)

    Over the last couple of days I have learned a lot from the forum. I thank all the participants for sharing their knowledge and wisdom.

    My problems are as follows:

    After dropping in a new battery, I could see there was very little fuel (and no visible oil on the cold engine dipstick). I added half a can of SeaFoam, let it jostle around, then trailered it to the gas station and put in 10 gallons of ethanol-free gas, and the rest of the SeaFoam.
    I then pulled the spark plugs, cleaned them off with some carburator cleaner, reinstalled them and it fired right up.

    After 30 seconds (on the trailer), I checked the oil and saw it was above "Overfull." I suctioned out just under 0.5 liter.

    It continues to start up the first time every time. I have dropped it in the water, but nothing changes: the throttle is simply unresponsive.

    The check engine light is on and the red light flashes, but it doesn't show any other warnings.

    I pulled the top MAP sensor and it looks perfect.

    The wastegate assembly is not locked up.

    All nine fuses look perfect, without a hint of corrosion.

    I have attempted to reset the ECU by pulling on the throttle repeatedly in the fashion prescribed on the forum. I've pulled the relay while it's running. I've installed the lanyard but not tried to start it, then removed the lanyard, waited, and nothing changes. I even pulled the red lead off the battery while it was idlng in hopes of resetting the computer.

    I am loathe to remove parts that will give me access to the lower MAP because there was no hint of any oil on the top MAP sensor, and I'd just as soon not replace the factory hose (crimped) clamps with inferior worm drive clamps.

    I can't figure out how to remove the three wire harnesses from the ECU. They have some light grey lock mechanism that I can't outsmart.

    Is there any hope of getting a proper diagnosis? I live in Southern California, fwiw. I wouldn't pulling the ECU and sending it to be reflashed, but even that might be difficult to accomplish anymore. Is there a way of "clearing codes" or getting it to escape limp mode. (To reiterate, this is real limp mode where it won't go above 1500 RPM.)

    Many thanks in advance!!
    Last edited by Wukinpanub; 06-25-2019 at 10:14 PM.


  2. #2
    Moderator HiPeRcO's Avatar
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    Welcome to Greenhulk! Unplug the single wire that goes to the exhaust temperature sensor, it's a good chance that's your issue. If not then it's a ETB/PPU issue.

  3. #3
    Thank you for the suggestion. I removed the single wire to the exhaust tempv probe. It made no difference.

    I then removed the PPU, started it up, and it was exactly the same.

    I then removed the SIFB, and then it wouldn't start. Hooking it back up got it to start again, but it was exactly the same as before.

    I then took a look at the throttle body butterfly (flutter) valve. I couldn't open the flutter valve, even with decent pressure applied with a screwdriver. I removed the four hex bolts and took it out of the machine. I popped six clips and took a look inside the Weber Motors/Bosch servo, and could see some corrosion. I dipped a toothbrush in CLR and scrubbed all the parts, then blasted them with some carburator cleaner, sanded the copper prongs, then reassembled it. I put it back in the ski and (in reverse) I now get 3500 RPM, so that's a huge improvement. I'll put it in the water tomorrow and see how she does.

    Thanks for all the help!!
    Last edited by Wukinpanub; 06-25-2019 at 10:22 PM.

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