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  1. #1

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    Intermittent drops in rpm. Help?

    My turbo ski has a problem I can't seem to figure out. The power has been degrading and it is somewhat intermittent. I'm seeing fluctuation of the rpm of up to 400 rpm. It's dropped as low as 7100 at full throttle and full boost (14 psi). It runs fine in the mid-range, but idles rough sometimes.

    I checked compression and got 125 psi on all cylinders. No air is coming out of the oil fill hole when running. I did leak-down on 1 cylinder and got only 5% so the long-block seems ok.

    I replaced all spark plugs today and got no change.

    I totally bypassed the AEM F/IC and ran the stock injectors today at only 10 psi boost. It would pull 7100 - 7400 but still surge.

    As of now, I have a stock engine, stock harness, stock injectors, stock ECU, but running a turbo. I can't see how the turbo could effect idle, though, so that's pretty much ruled out.

    Any ideas??? I'm almost out.

    Thanks!
    Mike


  2. #2
    not fast enuf rwells173's Avatar
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    could be a leaky intercooler
    Quote Originally Posted by engineermike View Post
    My turbo ski has a problem I can't seem to figure out. The power has been degrading and it is somewhat intermittent. I'm seeing fluctuation of the rpm of up to 400 rpm. It's dropped as low as 7100 at full throttle and full boost (14 psi). It runs fine in the mid-range, but idles rough sometimes.

    I checked compression and got 125 psi on all cylinders. No air is coming out of the oil fill hole when running. I did leak-down on 1 cylinder and got only 5% so the long-block seems ok.

    I replaced all spark plugs today and got no change.

    I totally bypassed the AEM F/IC and ran the stock injectors today at only 10 psi boost. It would pull 7100 - 7400 but still surge.

    As of now, I have a stock engine, stock harness, stock injectors, stock ECU, but running a turbo. I can't see how the turbo could effect idle, though, so that's pretty much ruled out.

    Any ideas??? I'm almost out.

    Thanks!
    Mike

  3. #3
    speedskixp's Avatar
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    leaky BOV maybe.

  4. #4

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    Quote Originally Posted by speedskixp View Post
    leaky BOV maybe.
    I could actually watch it while riding and see it wasn't opening . . . even when it was supposed to, but that's a problem for another time.

    Mike

  5. #5

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    Quote Originally Posted by rwells173 View Post
    could be a leaky intercooler
    That's something to check. I could pull off the pipe leading from the IC to the throttle body and power it up to see if water comes out. It is a fairly new XS intercooler. Probably 6 months old with maybe 10 hours run time on it in fresh water.

    Mike

  6. #6
    speedskixp's Avatar
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    Quote Originally Posted by engineermike View Post
    I could actually watch it while riding and see it wasn't opening . . . even when it was supposed to, but that's a problem for another time.

    Mike
    Are you sure it is not stuck open a little bit? I guess you wouldnt be getting full boost then huh!
    Last edited by speedskixp; 06-30-2008 at 08:30 PM.

  7. #7
    not fast enuf rwells173's Avatar
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    Quote Originally Posted by engineermike View Post
    That's something to check. I could pull off the pipe leading from the IC to the throttle body and power it up to see if water comes out. It is a fairly new XS intercooler. Probably 6 months old with maybe 10 hours run time on it in fresh water.

    Mike
    i just got an xs and it might be leaking. i need to check it myself. i have been having a similar problem

  8. #8
    speedskixp's Avatar
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    Quote Originally Posted by rwells173 View Post
    i just got an xs and it might be leaking. i need to check it myself. i have been having a similar problem
    I'm not sure but it seems to me that it would spit and sputter some if the ic was leaking. Maybe not alot but you should here some misfiring at WOT.

  9. #9

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    Quote Originally Posted by engineermike View Post
    My turbo ski has a problem I can't seem to figure out. The power has been degrading and it is somewhat intermittent. I'm seeing fluctuation of the rpm of up to 400 rpm. It's dropped as low as 7100 at full throttle and full boost (14 psi). It runs fine in the mid-range, but idles rough sometimes.

    I checked compression and got 125 psi on all cylinders. No air is coming out of the oil fill hole when running. I did leak-down on 1 cylinder and got only 5% so the long-block seems ok.

    I replaced all spark plugs today and got no change.

    I totally bypassed the AEM F/IC and ran the stock injectors today at only 10 psi boost. It would pull 7100 - 7400 but still surge.

    As of now, I have a stock engine, stock harness, stock injectors, stock ECU, but running a turbo. I can't see how the turbo could effect idle, though, so that's pretty much ruled out.

    Any ideas??? I'm almost out.

    Thanks!
    Mike
    Ohm your air preasure sensor or air temp sensor..... this $hit will make you crazy?

  10. #10

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    Today, I brought it to the river with the seat and cowl off, a WBO2 installed, and the charge pipe disconnected. Unfortunately, I didn't get to check the WB or the charge pipe for water leaks.

    When I started it, I noticed exhaust in the hull. After some investigation, I found that the downpipe had come loose, leaving about a 1/4" gap between it and the turbo. I'm not sure if this was causing the problem, but I fixed it and will have to go try another day. . .

    Mike

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