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  1. #1

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    1390 EFI Question

    The stats: LH ported PV-pinned 1390. EFI set at 7-11-9-8.

    The weird issue: Ski runs cleanly everywhere, although it will load up a bit when idling for a long time. But, when cruising at ~4K rpms, the ski will suddenly slow down like it fouled it plug, then accelerate, all while maintaining the same throttle position. Then it will repeat.

    The question: Is this normal for a ported ski, or for a ski with pinned PVs?

    Eric


  2. #2
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    Quote Originally Posted by Gipper View Post
    The stats: LH ported PV-pinned 1390. EFI set at 7-11-9-8.

    The weird issue: Ski runs cleanly everywhere, although it will load up a bit when idling for a long time. But, when cruising at ~4K rpms, the ski will suddenly slow down like it fouled it plug, then accelerate, all while maintaining the same throttle position. Then it will repeat.

    The question: Is this normal for a ported ski, or for a ski with pinned PVs?

    Eric
    When you say slow down how much are you talking about. When you hold it steady at mid range ported 1390 don't like steady holding throttle especially with pinned power valves. Try to lower your last pod from 8 to 6 that might help.

  3. #3

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    Thanx for the reply

    Can't tell how much it slows down, but it is probably around 20 MPH. Quite a dramatic difference.
    With the last pod at 8 the crossover is 6K RPM. At 6 it will be 4K RPM. I can try that, but that is right in the range where the "issues" occur.

    Eric

  4. #4
    WATER WOODY's Avatar
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    Is it when you squeeze the trigger at 4k? Try like Jim said and bring the high speed circuit in earlier.

  5. #5
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by Gipper View Post
    Can't tell how much it slows down, but it is probably around 20 MPH. Quite a dramatic difference.
    With the last pod at 8 the crossover is 6K RPM. At 6 it will be 4K RPM. I can try that, but that is right in the range where the "issues" occur.

    Eric
    Jim is correct... you want the red light coming on around 4600-4800

  6. #6

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    It happens when the throttle is held steady. I will set the crossover to come in at 4800 RPMs and see if that cures it. Thanx.

    Eric

  7. #7

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    OK, it seems like the crossover is the problem. Here's a weird idea - what if it just never... crosssed over?

    I have no PVs, and I could set the crossover above the max RPM. Will the EFI be able to keep up without the crossover to top end fueling?

    Eric

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