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  1. #1
    Moderator Franko's Avatar
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    The Saga Continues

    Well, for those of you who don't know about my issues, I have an RR stage 1 on my RXP. With the racing ECU, from the very beginning, I could only get 7650 RPM's. When I put my stock ECU on, I get 7900-7950 RPM. I have checked, double and tripple checked everything. Bought a new knock sensor - same result. Put in a new air intake system - same result. Reconfigured exhaust hose to eliminate crimping - same result. Tried thee vastly different pitched props - same result. I even swapped throttle bodies and racing ECU's with Jarrett who is running ~8400 RPM. Same result every time - 7650 RPM.

    At Mudbug, I discovered my intercooler block off plate lost its O-ring and air was escaping there. AHA! I found my problem. Well, no I didn't. I replaced the O-ring and took it out today. Guess what - 7650 RPM. At this point, I don't even know what to check. Back to the drawing board. Any suggetions?


  2. #2
    R.I.P. 11's Avatar
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    Yellow RXPs were the first produced, I think I remember hearing about some changes being made after the first batch.

    Have you tried Jarrett's stock ECU?

    That is the first thing I would try because if it doesn't run right with his stock ECU it means you have a different, early spec.
    Maybe the RR ECU works with later RXPs.

    I have been around Siemens injection/ignitions a lot when I was working for BMW and they have a very bad habit to change specs ALL THE TIME, maybe that's where you want to look.

    And then to be sure I would try your stock ECU on Jarrett's ski.
    11

  3. #3
    Site Admin Green Hulk's Avatar
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    damn! damn! damn! im out of ideas Frank.

  4. #4
    Site Admin Green Hulk's Avatar
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    Frank, have you done a compression check on your engine?

  5. #5
    Moderator Franko's Avatar
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    I discovered my intake grate is broken. One of the bars is completely separated from the pump end of the grate. The other bar has the same crack and will break shortly as well. Luckily, I ordered a Riva Grate this week. But this doesn't explain my problem. My next troubleshooting venture is electrical. When I removed the stock air intake, I cut several wires. I think I spliced tham all back together, but I guess there could be one that I didn't get. But that doesn't explain why my stock ECU runs fine, but the racing ECU doesn't.

  6. #6
    .......or maybe you just got a poorly,or mis-programmed ECU........

    if the RPM's come back up after an ECU switch,I would think a compression test would be a moot point.

  7. #7
    R.I.P. 11's Avatar
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    You should definitely try Jarrett's stock ECU.

  8. #8
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by Franko
    When I removed the stock air intake, I cut several wires. I think I spliced tham all back together, but I guess there could be one that I didn't get.
    Frank! Not good! This could certainly have something to do with your low RPM's.

  9. #9
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by SKR8PN
    .......or maybe you just got a poorly,or mis-programmed ECU........

    if the RPM's come back up after an ECU switch,I would think a compression test would be a moot point.

    He tried Jarrett's known good RR ECU with the same results. It's not an ECU issue.

  10. #10
    R.I.P. 11's Avatar
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    Quote Originally Posted by SKR8PN
    .......or maybe you just got a poorly,or mis-programmed ECU........

    if the RPM's come back up after an ECU switch,I would think a compression test would be a moot point.
    Then why Jarrett's ECU, that works perfect on Jarrett's ski doesn't on Frank's?

    Why Frank gets more out of his stock ECU than he gets out of his RR?

    I still say early spec ski that doesn't accomodate the ECU that has been designed for a later spec.
    11

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