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  1. #1

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    MSX 150 tops at 3550 rpm

    Hello,

    My MSX 150 will not rev above 3550 RPMs (10 mph). It starts fine and revs up to 2400 rpm until itís been running for about 10 minutes then it tops out at 3550 rpm. It idles at 1450 rpm and will only rev to 2450 RPMs when in reverse, cold or warm. There are no flashing lights or warning messages on the display. It has 70 hours on the meter.
    >>
    The last few times I was able to run it, the engine would run roughly and nowhere near full power at start-up. After 10 to 15 minutes of varying the throttle input it would eventually take off and run fine. >>

    The last time this happened it ran at top speed for about 10 minutes then the power cut out while at full throttle. I puttered back to the dock at 3550 RPM with the throttle wide open. >>

    I replaced the fuel filter, but that did not change anything. >>

    I have read the threads about the failed IFB module and the 3400 RPM reverse limit. >>

    My engine will rev to 3550 RPMs forward and 2450 RPMs reverse at full throttle.

    Does this sound like an IFB failure? How can I check it?


    Thanks
    Clay
    Last edited by Clay; 08-13-2013 at 02:56 PM.


  2. #2

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    Aug 2012
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    5
    From what I have read, and my recent experience with a failed SIFB (system interface board) with one of my MSX 150's...this is probably what you're dealing with. Martos Motorsports has a replacement SIFB for $299 plus shipping. I suggest giving them a call and talk them through your issue. John at Martos was very helpful to me earlier this week.

  3. #3

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    Thanks for the help. I'll give him a call.

  4. #4
    ripcuda's Avatar
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    $299? UUGGGHHH! Percentage-wise... that is worse than the domestic CDI's being sold. I helped test the prototypes of these being sold.

    Anyways.... It does sound like the SIFB is causing your troubles. And sadly... there aren't any other options out there to get replacements currently.

    Have you done a compression test lately? That's a very good gauge of engine health in these Webers.
    Also... check intake for signs of oil ingestion. Fouled MAP sensors can cause all kinds of erratic running problems.

    Cheers!

  5. #5

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    Thanks Ripcuda for the advice.

    What's the saying about a boat being a hole in the water.


    Is there anyway test the SIBF module once it's removed from the engine?

    They seem to be a common problem. Are the replacement units any more reliable?


    Can the MAP sensor be cleaned and if so, what's the best way to clean it? Or should it be replaced?


    Thanks again

  6. #6
    ripcuda's Avatar
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    I do not know of any way to test the SIFB off the ski. Bad ones are usually easy to spot based on the troubles they give you on the ski so I've not needed to try and test one off.

    The new aftermarket SIFBs have only been developed in the last year or so and only recently for sale. So no long term reliability record yet. But they seemed a solid product... the ones I tested. I wouldn't worry too much about them. Not like there are many choices.

    As for the MAP... what usually goes bad in them is a sensitive filament that detects air temps. These MAPs have 2 parts... the pressure sensor and the temp sensor. On the Weber, both MAPs (which are identical) are used for pressure sensing... but only the one on the hardpipe is used for sensing air temps. You may notice that wire connector has 4 wires.... whereas the wire connector for the one on the intake manifold only has 3. When these are oil fouled and/or cleaned... it's the filament that gets damaged and then sends wonky air temp readings to the ECU. You could try to clean them with some sort of sensor cleaner... but warm soapy water may be the best. Most folks don't seem to have luck trying to clean them... not sure what they use... and thus buy new ones (~$45 from GM direct).

    Don't forget to run a compression test. You'd be throwing $$ to the wind if you have bad compression.

    Cheers!

  7. #7

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    I removed the MAP sensor and it was covered in a film of oil. How does the oil reach the sensor?
    Is this common, does it need to be replaced periodically, or is this a sign of another problem that oil is getting on the sensor?

    The throttle body looked clean.

    Thanks

  8. #8
    ripcuda's Avatar
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    Yeah... that's not good. Sign of oil ingestion... which is all too common on this ski.

    Which MAP did you pull... the one on the hardpipe?

    To confirm or rule-out oil ingestion... you have to pull the turbo-to-intercooler hose, the intercooler-to-intake hardpipe and hoses and visually inspect them inside... including the intercooler as best you can. Oily sludge or gunk in there is bad. A very slight oil film on the pipes or hoses... that you can barely feel between your fingers is pretty normal.

    Oil ingestion is caused usually by over-filling the oil tank (improper dipstick oil level checking method)... which spews the excess oil into the oil separator (cyclone... side of oil tank by battery)... which can't handle that much oil that fast and the constant suction from the emissions recirculation hose that leads from the cyclone all the way back to the airbox just starts sucking all that oil back through the hose... into the airbox... into the turbo... and all through the intake tract. If enough oil gets sucked in... it'll gunk up your intake hoses, the intercooler, foul the MAP sensor on the hardpipe... and in extreme cases even make it all the way into the intake manifold. These fouled MAP sensors send wonky reading to ECU which gets all confused and doesn't run right... sometimes tripping trouble-codes.

    If this happens... you gotta get all that oil cleaned out. The worst part is cleaning the intercooler. It is hard to remove with the engine in-place... gotta come out the front after dismantling the steering column. I use hot soapy water to clean all the hard pipes, hoses, intercooler, intake manifold (I had pulled the engine). If cleaning the intake manifold while leaving it in-place... remove the throttle body to access the larger hole under it and use brake clean or carb clean to clean as best you can. Clean the TB too.

    After getting all the mess cleaned out. Remove that emissions recirc hose to prevent from happening again. Plumb the cyclone off into an oil catch can... or just put a filter on it... you don't want water getting in there or it'll get in the oil.

    Also... figure out why it happened in the first place. Too much oil? Is your oil foamy show signs of water in it? Water or coolant getting into the oil will foam it up and that too will get sucked back through the recirc system.

    If you need a new MAP sensor... you can get the exact same Bosch part through GM parts direct for about $45.
    Both MAP sensors cross ref to '06 Chevy Cobalt SS' MAP sensors ($45 on ebay)
    Bosch 0261230042
    GM 90423637 (use gmpartsdirect.com) $45

    Cheers!

  9. #9

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    I checked the two hoses and the intercooler. The intercooler pipes are clean. The hoses had only a thin film of oil. You can feel it between you fingers, but it's clear.
    No gunk.

    I pulled the MAP sensor from the bow side of the intake mainfold. The one in the pipe at the intake hose is clean.

    The oil on the dip stick looks clean, not cloudy. Same with the coolant.

    I've always been careful when changing the oil to mind the level.

    Is there error in the manual in reference to checking the oil level or a problem with the dip stick marks?


    Clay

  10. #10
    ripcuda's Avatar
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    I don't recall what the owner's manual says about oil checking procedure... but the sticker put on the stock oil tank near the dipstick is correct. But not having seen one of these skis new, I don't know if came that way from the factory or was later put on to clear up the confusion.

    When most people think of checking oil on a dipstick... it's not required to start the engine for a period of time then turn it off before checking. Most dipsticks like the one in your car or lawn mower can be checked cold. If folks do that on the MSX 110/150... and then fill the oil up between the MIN and MAX mark... there will be WAY too much oil in the system.

    See the oil tank is higher than the sump... so as the ski sits for a while the oil in the tank eventually ends up in the sump and hoses to/fro... making the oil in the tank lower. So if you read the dipstick in this state, it looks low... so you might add more to get it between MIN and MAX marks. BUT... after you start the engine for even just 20 seconds... that will move all the oil in the sump back into the tank bringing it back up to the proper level for checking.

    So checking after running 20 seconds on a cold engine... you want the oil somewhere between the bottom of the dipstick and the MIN mark. Then after you run the ski and everything is up to temps... when you turn off the engine... and check the dipstick the oil will be somewhere between the MIN and MAX mark... exactly as it should.

    Oh... and don't screw in the dipstick when checking.

    Cheers!

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