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  1. #1

    Join Date
    May 2008
    Plano TX

    RXT Slight Miss, Variable RPMs, Please assist!

    Gentlemen and Ladies;

    Thanks in advance for your assistance. I have been searching the threads for help; but I am at ends with this issue. I have seen some similar posts with variable rpm issues (up high) and almost feel like we have something in common.

    I have 2 RXTs (both 2006) so subtle differences are easier to detect. Here is the current problem with my 2006 RXT - 29 hours.

    At idle there is a slight vibration that I would call a slight miss. The engine does not feel to run as smooth at idle as the other RXT (even the wife noticed). When beginning to throttle; if I hold the rpms between 2200 and 3,000 rpms I can hear a slight miss (and see the rpms hopping around by 1-200 or so). Once I bury the throttle this miss is not there...however:

    At WOT I do have another issue. Depending on the alignment of the may have more or less power. Sometimes it is quite pleased to jump up to 7700 rpms then quickly build to 8100 rpms...other times it jumps to 7300 rpms..builds rather quickly to 7700 rpms, then eventually gets to 8000 rpms. From experimentation so seems to do this (retarded mode) after flogging the beast in tight circles, or otherwise rough play. After a long jaunt, she seems to get her power back.

    BTW - Water temp 87 degrees, no open thermostat mod, stock IC.

    These symptoms have been present both before and after a few mods that I have done. I have replaced the clutch on the SC to metal washers, didn't fix it (although I sleep better now). Removed the SC again and checked the slip moment (I think it was at like 90). Then, while it was out I upgraded the blower and put in 42 lb injectors (made a bit of difference power wise (could only get to 7800 rpms before, now 8100), but the pesky roughness and lack of power are still there).

    Then I had a problem with getting too much H2O in the boat..thanks for the threads on the RULE pump..this is an awesome setup. Also had a problem with the dash board...would not function at all. Had to get a new one of these. Oddly enough, it reset the ski from 19 hours to 2 hours?

    Back to the original problem - it almost feels electronic to me. With this rough (and ever so slight) miss at idle...then at 2200-3200 rpms (noticeable slight miss) then this varying power problem up high (may be related to temp?) I was initially thinking O2 sensor. I have since learned this does not exist (it is an EGT device).

    Now I am trying to get feedback on any sensors or other reasons that would cause this. Don't know if the knock sensor thing applied to 2006 models? Of course, I already have changed the plugs twice, checked the oil level, said a prayer to SeadooMaximus...all the usual.

    I would appreciate any help on this!

    PS - The other RXT doesn't have these issues in the 87 degree water. I know I should prep for the warm weather, but I am 2 months away from moving to Pennsylvania (where water temps will not get over 70-74) so I don't want to go there yet.

    Thanks again

  2. #2


    Try putting the set of good coils from your other ski into the problematic one??
    Easy enough to try.

    Maybe throttle position sensor (situated under throttle body)

    hope you do get to the bottom of this one

  3. #3
    I wanna hear the results cause mine does the exact same things you are discribing - Im at 25hrs.

  4. #4
    Been there and back! BDNJ's Avatar
    Join Date
    Jul 2005
    Silver Bay, Toms River, N.J.
    Hey Joe - what s/c did you upgrade to???? You might not need the 42's at all. Do you any type of fuel controller along with the 42's? I think your coils are probably ok since you have such a low-hour unit. Just in coils are the long, black connectors that go down the spark plug holes and connect directly to the spark plugs. The coils can split or crack with age and wear. Typically a cracked coil will cause the boat to lose spark and run very, very roughly.

    Another posibility....check your throttle cable at the rear of the intake manifold. With the ski off, hold the throttle wide-open and verify that the cable is actually hitting the stopper on the other end of the line.


  5. #5

    at idel speed shoud be 1800 rpm if not then

    try to remove idel by bass valve , instal the key to chk if it is working.

  6. #6

    Join Date
    May 2008
    Plano TX

    Back to the RXT troubleshooting

    Sorry Gents and Ladies for the long wait on reply..I was without internet connection for the week.

    The RXT did this thing before upgrading the SC and going to the 42lb injectors. I do not have a fuel controller of sorts, but I neglected to mention the blow off (I did add this).

    Thanks to BigTreads for the feedback. What other symptoms do you notice?

    My Course of Action for this afternoon:
    1) I will look at the coils today and swap with the other RXT
    2) I will check the throttle linkage / stop
    3) I will try to figit with the throttle position sensor.

    A question for medo00ska: With the throttle bypass valve...If I remove it, what should it do when working? What does it look like?

    Also - What symptoms would a bad knock sensor cause?

  7. #7
    Thats about it for symptoms - other than at one point the slight miss became more like a totally dead cylinder. That was with a passenger that didn't want to go fast resulting in the condition worsening. Unfortunately due to the weather (and life) I haven't been able to get out on it for 3 weeks so at this point Im not much help. Can we really be the only 2 people with exactly the same problem here ? Kinda makes me go Hmmmmmmm

  8. #8
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Mesa, AZ
    J-pipe may be leaking

  9. #9

    Join Date
    May 2008
    Plano TX

    RXT Engine Miss Update

    Yesterday I took the ski out for the usual weekend workout. The miss is getting slightly worse with time. I Did get an error code (P1544 Exhaust Temp) - Which at first glance looked like "piss'd" which I agreed with. The P1544 code came only once while doing tight circles; then didn't do it the rest of the day.

    Checked the J-Pipe this morning..didn't see anything out of the ordinary. Started it up and poured some water--could not see any leaks (thanks for the recommendation to check the J-Pipe). Felt around it while running to check for leaks as well (best I could without getting burnt). Where does the J-Pipe usually leak?

    I have bitten the bullet and taken it to the Seadoo Dealer (I cringe writing that statement). My suspicion is that it will take them 2-3 attempts to get it figured out (so the resolution will be in about 4-5 weeks)??? I will update the group on the horror story as it unfolds (Chapter one is taking the ski to the dealer...Chapters 3-5-7 are going back to the dealer for the original problem in Chapter 1; Chapter 2-4-6 is finding another job to pay the dealer for all the overcharges; Chapter 9 is settling for an engine miss or trading the ski in!)

    Bigtreads: I agree - we can't be the only 2. I am saying Hmmmmm and starting to feel like a Harley Davidson owner (from the old Yamaha R1 days we would laugh as we spent more time ridinng than working on the machines)

    I will keep the group updated

  10. #10
    speedskixp's Avatar
    Join Date
    Feb 2008
    venice fl.
    My ski was spitting and sputtering and it turned out to be the battery. Even though it started ok. It must of had a short in the battery. No problems sense.

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