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Thread: Low RPM Dilemma

  1. #1
    Boost-A-Holic's Avatar
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    Low RPM Dilemma

    Ok so once again ive got an issue with my ski that i just cant seem to figure out so i figured id see what you guys think. It no longer wants to rev past 7600-7800 RPMs. After consulting the data logs it literally appears that my rev limiter has been lowered somehow. Ive got plenty of power and all seems to run well but as soon as i give it any more than 50% throttle it just bounces off 7800 and will drop a lil if i try to stay in it. AFRs are spot on and everything from TPS Calibration to my duty cycle percentages all are in the green. Nothing of concern with the tune or anything i can see from the data logs.

    Wear ring is good along with the rest of the pump, supercharger slip is perfect, no boost leaks at all, i put a fresh set of plugs in it yesterday and even tried a new set of coil packs. Much to my dismay the problem persists.

    My next move is to get candoo hooked up and see if it can detect whats going on.

    any input is much appreciated as im trying to get my ski squared away before Mud Bug.


    its an 09 RXP with an ET-137, Deka 80s, Box n thru hull, 15/21, 82mm nozzle, 4" intake, Stock Siemens ECU with CMD + Auto-tune, Fizzle H/E, and a bunch of other small mods.

    It was running fine with the Bosch 50s but my duty cycle was at 100% at 7800 so i had to step it up on the injectors....RPMs where at 8160

    another small side note ive had an issue with my boat drawing power (prolly a relay) even when its off so ive been unhooking the negative side after every ride and hookin it back up before the next one.

    thanks,
    Troy


  2. #2
    GasResearch-VT.SE's Avatar
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    I've had a ski here in the same sort of dilemma.

    The only 4 things I haven't checked yet are: Cam timing, engine alignment and I have had an on-going problem with splitting manifolds @ ~15psi.

    So a new aly manifold is here, but haven't done any water test after.

  3. #3
    West Texas RXP skoepp's Avatar
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    If was fine with 50s something happen not right when changed injectors.
    Big difference from 50s to 80s.
    Might work it backwards.
    Try the 50s again, go from there, what I would do.

  4. #4
    Mod less, ride more! troyheb's Avatar
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    You say you have an electrical problem. I would fix that first. It could be the problem.

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    Quote Originally Posted by troyheb View Post
    You say you have an electrical problem. I would fix that first. It could be the problem.
    The relay has been drawing power since before i ever changed out the 50s and it never caused a problem then so i wonder how it could be now....ill definitely fix it i just don't think thats the cause.

    Quote Originally Posted by skoepp View Post
    If was fine with 50s something happen not right when changed injectors.
    Big difference from 50s to 80s.
    Might work it backwards.
    Try the 50s again, go from there, what I would do.
    I tried a set of 48s my buddy had lying around as i had already sent my 50s back and it still is doing the same thing. Im gonna try some 50s prolly some time this week.


    thanks for the input you guys i appreciate it

  6. #6
    Moderator beerdart's Avatar
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    Hook it to candoo and see what your MAP reads with the engine off.

  7. #7
    AtoMIC_OraNGE greenbullet's Avatar
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    With candoo like beerdart said check the map reading and reset tps at the same time. It will run on 50s. I'm running a 68-140 on bosch 48s with a walbro pump rrfpr and a begi just fine.... I will change to 50s probably when I install the riva ecu

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    Candoo it is.....i just need to get a vin first lol

  9. #9
    imp0ster's Avatar
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    knock. A bad injector (and the dekas squirt like a hose instead of atomizing) will heat up one cylinder causing knock at a certain RPM which would cause the rev drop. You adjust your fueling to get the correct AFR and would never know one injector isn't doing its job properly.

  10. #10
    Eric Ocman's Avatar
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    Imo the siemens injectors are crap but it seems you're problem is elsewhere. Have you tried disabling you're cmd?

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