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  1. #1

    2004 MSX150 idles at 3400 rpm rev limit

    newly aquired 2004 msx150 idles at 3200-3400 rpm rev limit. I have searched the net, greenhulk, pwctoday, talked to randy at webber power, etc... this is not an easy fix lookin for the resident guru on polaris 4 stroke and weber turbo electronics.

    Brief history on the ski: aquired from a customer that had give up on dealership and lost interest in ski and pretty much just gave up on the ski. Ski came in to me as a water injestion problem with white milk in engine oil, tank, lines, hull, intake, cylinders, etc... I changed oil, opened the cleaned it and installed, removed intercooler cleaned and installed, bypassed water around oil tank and oil cooler in front of engine, drained coolant, pressure tested engine, did compression test, replaced spark plugs, cleaned intake, checked fuel pressure, checked wastegate, and dump valve, checked all hoses and cleaned, checked both map sensors and replaced one with temp gauge with new, disconected exhaust temp gauge, checked esp and reverse for proper operation, checked ppu sensor, and etb for proper operation, checked sifb for proper operation, placed ski in comm mode out of sleep mode and hooked to digital wrench. Did a 30-45 min boil out of engine running on hose, changed plugs again (fuel fouled? very dark not like a oil foul), changed oil and filter. removed fuel and replaced, replaced fuel filter, cleared trouble codes. hooked regular cooling systems back up.

    Now there are no trouble codes, engine idles at 3200-3400 rpm, moderate white smoke from exhaust, battery is fully charged 12.9v , ppu at 0, tps 1 ppu .2v, tps 2 ppu .3 v, tps 1 etb .4v, tps 2 etb 4.8v, (these are from memory on digital wrench may be a little off) only component not repaired is the exhaust temp sensor and its disconected digital wrench sees it as a fault positive. 150 hrs on ski, bore scoped both cylinders no scars nicks dings no nickal seal missing, both cylinders 140psi. cooling system holds 10psi empty. 13.8v at battery while running, water pump working like new. 3 quarts of 15w50 mobile one poured in at oil change. Any takers on what could be wrong with this thing? its my first polaris 4 stroke i didnt even know they existed until about a month ago. I work on all makes of npersonal watercraft for a living and usually get all the stuff nobody else can figure out this ski is eating my lunch, somebody has to know what is up here.

  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Welcome to the Polaris forum

    I am sure some of the Weber guys will be along soon enough.

    For clarity, what did you mean with this;
    "... I changed oil, opened the cleaned it and installed ..."

    I can tell you that after you get the engine sorted out you need to remove and rebuild the through-hull bearing carrier. The recommended replacement interval is roughly 100 hours.

    In addition, the normal maximum run time on the garden hose is two minutes. The reason is the seals in that through-hull are normally water cooled when the hull is floating. Running it on land overheats the seals after just a few minutes. Once the seal lips are melted or worn, water gets inside and rusts the steel bearing.

    If the bearing seizes to or damages the driveshaft then not only does the drive shaft need replacement, but the engine may have to be lifted to get the seized bearing + driveshaft out of the hull from the inside.

  3. #3
    I forgot to mention that before I did the boil out I unbolted the pump and slid the whole assembly back far enough to disconect the drive coupling and then put some pieces of inch and a half angle between the pump housing and the hull so the coupling wouldnt try to reingage, so no worries there, thats the same way I do it on the 4-tec. except I can pull the whole pump or just disconnect the drive.

    I found out most of my worries were cooming from the plugs after I pulled and changed them yet again, this thing is running supper rich after I changed the plugs it idled up high then settled back down after a few seconds to 1400-1500 rpm so idle is down now where it should be. throttle is responding now and turning up to around 3400 at limiter with reverse lever up. The high during the day is about 45 degrees here so i have not been able to put it in the water. Its suppose to be 42 degrees to even attempt the ebt learn. Does it matter what kind of plugs I am using I am not using iridium plugs they are the ngk bkr7e plugs and are not lasting very long, so i bought some iridium autolite seems to idle a little better but not a huge difference just cuts down on the rpm hunting. Also I pulled both plug boots off the coils and screwed the springs into the threaded end of the coil one of the springs was just floating in the boot.

    When I said I changed the oil, cleaned replace. What I meant to say was I drained the oil, removed the tank, opened it up, cleaned it, put it back together and installed it.

  4. #4
    the only other thing I can figure that is fouling my plugs, causing excessive exhaust smoke, rough idle, etc... is my head gasket could be leaking letting coolant into the combustion chamber and coolant fouling the plugs, is there anyother place that coolant could get in and foul the plugs besides the head gasket? could it be coming in through the intake somewhere like the turbo or something crazy like that, that I would have to hunt forever to find that everybody already know is a known problem or some similar scenario?

  5. #5
    ripcuda's Avatar
    Join Date
    May 2010
    Newman Lake, WA
    Welcome to GH!

    It sounds like you really know your way around a pwc. And the fact you have Digi-Wrench already gives you a big advantage to troubleshooting these turbo Webers. I've never had the chance to use DW. We around here are forced to interpret the ECU rev-limits to point to possible problems. The most knowledgeable guru for the electronics for these Bosch ME7.4.4 turbo Webers is Martin (Desperado) at Precision Sports. He's even developed a reflash for the MSX 110/150 ECU for more power.

    That said... extended running on the hose just isn't the same as putting the ski in the water. Without a load on the pump... the engine is very prone to over-rev and the ECU has trouble getting the idle to settle down to the rock stead 1500/1550 that you'll see in the water. That is why we always keep reverse engaged when running out of the water. So if the revs zing way up... they won't go over 3400. When the ECU is holding it to 3400... I'm not sure if it's fuel (injectors) or spark that the ECU is using to hold revs... but I can see why extended running against that limiter would probably foul the plugs.

    When folks are recovering for issues of water in the oil... after they fix the problem and change the oil... we tell them to get out and run the engine good (in the water) to get it up to temps and to try and cook off any remaining moisture in the oil. This often takes at least 2 oil changes to be fully successful. I'm not sure you're going to be able to fully do this out of the water.

    Did you figure out how water was getting into the oil? Common issue is the oil tank. Old round metal tank was prone to leaking the cooling raw water that circulates around it into the oil inside (giant o-ring seal). So if you've bypassed the water around tank (probably not good for long term... helps keep oil temps down) then that should eliminate that for now. You said you bypassed the oil cooler? How? That log shaped cooler under the IC flows coolant thru it... not raw water. Either way... taking out the IC was a good step... gotta get all the oily sludge/foam out of the entire intake tract. Also consider rerouting the oil separator (cyclone, batter side of oil tank) hose that sucks back into the airbox... plumb that into an oil catch can... so it can't suck oily fumes/gunk back into the intake.

    You sure the turbo is good? Not a blown turbo seal? That could put oil into the intake too.

    The pair of MAP sensors are important to the ECU. The upper hard-pipe one uses the air temp filament in the sensor (4-wires) for intake air temp reading. One one the intake mani just reads boost (3-wires). These tend to get fouled via oil contamination so most folks replace them. I'm thinking you might be able to verify their proper readings via DW.

    As for possible coolant ingestion... are you loosing coolant as it runs? Level in coolant reservoir dropping? 140# compression in each cylinder is great. Have you done a leak-down test? That's a sure way to spot a blown headgasket. When I've done it on one Weber... it gurgled the coolant when doing the leak-down... so pretty obvious a blown headgasket. If the engine has ever overheated... a blown headgasket is a real possibility... happened to me.

    These are the recomended plugs: NGK BKR7E or Champion 3068 RC7PYCB... with the nod to the Champions.

    Oil is Mobil 1 15w-50 full synthetic. But many folks run something like Rotella 15w-40... for engine flushing... to get rid of the water out of the oil... then put in the expensive Mobil 1 when done.

    So... hope that helps. My own MSX 150 will idle out of water at 1550... if I don't touch the throttle. If I attempt to zing the throttle... it will rev sky high and hang there... which is why we use the reverse to hold it to 3400. But in the water... never had a run-away rpms.. always rock stead at 1550. Sounds like you are in the same boat.


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