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  1. #1

    Msx 150 over boost issue

    I have 2 150's. One runs great and one kicks out. I removed and cleaned map sensors and reinstalled. No change. I swapped wastegate solenoids. No change. Here is what it does. Runs great to about 6k rpm. You hear a loud pshhhhh and it goes into a flashing check engine and down to 4850 rpm. Shut off and it will do it all over again. Wastegates both move with the same tensions. What next? When I cleaned the map sensors the lower one had a very slight oily film. Top one looked clean. Is it possible to be a bad pop off valve?


  2. #2
    Iantryinit's Avatar
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    I had similar issue and found hose to inter cooler popped off(well loose at clamp). Also they have cuts or holes. Check all clamps on both sides. And near throttle body boot.

  3. #3
    Thank you for the advice. Are you saying to loosen the lock nut and extended the bar that goes to the wastegate lever by 1/4"?

  4. #4
    ripcuda's Avatar
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    Your overboosting... or so the ECU thinks... and it kicks in the check engine light and 4800 rpm limiter. The question is why...

    So you confirmed that the wastegate isn't seized or sticking... has same movement on both skis... okay.

    FichtEMMRepair guy is the only person who recommends adjusting the wastegate actuator rod length... and I'm not sure why (thinking manual boost controllers and adjustable wastegates like in cars??). Unless you've previously messed with the actuator... it should be set where it needs to be already. You don't adjust the boost levels by doing this when the adaptive Bosch ECU is controlling boost via the wastegate solenoid. The ECU will just relearn the solenoid timing needed to reach it's desired boost levels (eventually)... unless you make the actuator too tight or too loose... then the ECU won't be able to control it and you'll have problems.

    Weber... the manufacturer says this:
    3.5 rotations of the jam nut = 7mm of spring load



    Loosen the lock nuts and adjust the “eye” bolt until you can thread the 6mm screw in by hand. (it should thread into position easily), then tighten the barrel nut 3 ½ turns so you are “preloading” the wastegate.




    Don’t adjust the tension on the wastegate arm. It won’t help it build more boost, and will only make it ‘flutter” more as it goes into “overboost”

    I'd start with Iantryinit's advice. Look for boost leak points. Check the hoses and clamps. Check the throttlebody rubber mount. Look for possible pin-holes or tears in the rubber parts. Check the small hoses coming off the front of the intake manifold that Tee off to the blow off valve (bov) and to the fuel pressure regulator.

    Pull off the bov and inspect. If this is damaged... and can't hold the boost in (while getting a equal boost source via the small hose)... it'll blow off while your ECU is still calling for more boost... and could lead to overboost. Swap the bov with your other ski and see if that cures overboost.

    You could always swap MAPs between skis too... to confirm it's not that. Though it doesn't sound like MAP issues to me.

    Good luck... let us know what you find.

    Cheers!

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  6. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by FichtEMMRepair.com View Post
    Yes just keep extending it till the over boost goes away..
    If you shorten it that will give you more boost.

    I don't care what anybody says I have fixed 12 msx skis just buy extending the arm..

    The control valve gets week
    so the are will not open up enough but the control valve will work like that for a long time dont worry.
    So the core issue is the air pressure control to the waste gate actuator is out of specification. The waste gate is not moving properly in response to the control signals from the ECU to the solenoid. And the actual problem cause is the solenoid valve is leaking pressure, clogged or just not flowing air pressure in the proper manner. Have I got this correct?

  7. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Westranger1 View Post
    Thank you for the advice. Are you saying to loosen the lock nut and extend the bar that goes to the wastegate lever by 1/4"?
    Quote Originally Posted by ripcuda View Post
    ... FichtEMMRepair guy is the only person who recommends adjusting the wastegate actuator rod length... and I'm not sure why ...

    You don't adjust the boost levels by doing this when the adaptive Bosch ECU is controlling boost via the wastegate solenoid. The ECU will just relearn the solenoid timing needed to reach it's desired boost levels (eventually)... unless you make the actuator too tight or too loose... then the ECU won't be able to control it and you'll have problems.

    Weber... the manufacturer says this:
    3.5 rotations of the jam nut = 7mm of spring load

    Loosen the lock nuts and adjust the “eye” bolt until you can thread the 6mm screw in by hand. (it should thread into position easily), then tighten the barrel nut 3 ½ turns so you are “preloading” the wastegate.

    Don’t adjust the tension on the wastegate arm. It won’t help it build more boost, and will only make it ‘flutter” more as it goes into “overboost”
    ...
    7mm is about 1/4"

    Is the Harris recommendation simply to remove most or all of the preload tension on the waste gate rod?

  8. #7
    So what your saying is to lengthen the control arm a 1/4"

  9. #8
    ripcuda's Avatar
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    Have you checked all the more likely culprits to your problem as mentioned above first?

    Tweaking your wastegate actuator rod length should be the last resort... IMO.

    Cheers!

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