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  1. #1
    Moderator beerdart's Avatar
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    Missing 1000 RPM's

    Here is the deal on my conversion.

    I am down 1000 RPM's
    The facts.
    05 motor form a RXT 53 hours compression 140 across the board leakdown test 6% across the board.

    Stock SC slip is at 112 lb/in external intercooler e-bay spacial.
    Started with a big 14/26 prop 7100 RPM's changed to a 13/21.5 same RPM's changed to a 12/18 same RPM's. Coolant system has been leak checked and all is good. Boost gauge is showing aprox 6ish @ 7100. Fuel pressure is at 58 psi..

    Changed coils same results.

    Changed injectors same results.

    Its like there is a 7100 rev limit all RPM's checked with second Tach.

    AFR is 12.5 Idle and 13.4 WOT @ 7100.

    ECU problem???

    I dont know what to do next.


  2. #2
    Moderator RX951's Avatar
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    I'm still learning these 4-tecs, but a few questions;
    Can it be timing?
    Can the camshaft be the culprit? Lobes worn?

  3. #3
    JFizzleJR's Avatar
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    Is your ECU from that same RXT motor? Just throwing out ideas here, maybe you need the knock sensor update. This was known to hold stock skis back to 7400 without it. Was your TPS reset if the TB and ECU didn't come mated (from same ski)? Any idea why your AFR is so high? Stock supercharger, stock injectors? What air intake? Any idea what RPM the RXT ran before the motor was pulled?

  4. #4
    Moderator RX951's Avatar
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    I was goi g to ask that as well, is that ecu the right one? I would swap it with another one. Can a certain sensor hold rpms back?

  5. #5
    JFizzleJR's Avatar
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    I would check the MAP sensor and Intake manifold temperature sensor for shits and giggles.

  6. #6
    Moderator beerdart's Avatar
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    As far as I know the all the parts are from the same ski. I bought this motor with all accessories used so the history is unknown. The TPS has been reset and all codes cleared. All parts are stock except the IC... Timing was checked and is set to factory specs.

  7. #7
    beachbum0286's Avatar
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    I was missing 1000RPMs and just figured out my problem, a leaky intercooler! You should check yours.

  8. #8
    Prohibido usuario
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    Check boost #'s. My first thought was ECU also.

  9. #9
    JFizzleJR's Avatar
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    Quote Originally Posted by NCHeel View Post
    Check boost #'s. My first thought was ECU also.
    he said 6 psi slacker--at 7100, which is abnormally high for that RPM. I had a rotax high boost wheel (rated at 9-10 psi) at 1000 ft. elevation. I was seeing 8.9-9.3 with it at full RPM and then when it got warmer I was seeing 6's at only 7600 RPM.

  10. #10
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    AFR should be 11.8-11.9.....not 13's when on boost.

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