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Thread: Holley Sniper issues?

  1. #11
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    I was referring to disabling completely the CD box and just run the yellow coil negative wire from the harness to the coil negative, thus not using the CD box at all and disconnecting the purple & green wires. Maybe the issue is with the CD box or faulty coil, thus why he's not getting any RPM reading. Hopefully he understood my post, but it's always good to be extra clear here and I'm glad you brought it up.
    Last edited by RPnova; 03-25-2019 at 12:37 PM.

  2. #12

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    Possibly a dumb question, but wouldn't the car not run with out the MSD hooked up? I understand hooking the yellow wire to the negative post of the coil. I wasn't sure if disconnecting the tach output from the MSD box, and leaving it hooked up with the yellow wire to the negative terminal on the coil would do the trick.

  3. #13
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    Maybe I wasn't clear enough. As 81 Trans Am said, you can't use the yellow wire while your ignition type is a CD box. My thought was to temporarily disconnect the CD box. Most distributors have the orange & black or brown wire that goes to the ignition coil. So all you would do is hook up the yellow to coil negative, and the orange & brown wire from the distributor to the positive & negative of the ignition coil to completely bypass the CD box and you'll hopefully get a RPM signal to the ECU which is what you want. Conversely, it might easier to swap out your ignition coil with a known good coil to save a little time wiring. All I'm doing is troubleshooting and trying to eliminate one thing at a time. Are you using the white wire from the 10-pin harness? A engine can run without a CD box. Also, what's your fuel pressure at? Do you have a gauge?
    Last edited by RPnova; 03-25-2019 at 03:33 PM.

  4. #14

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    The distributor I have only has the purple &green connector, and a power hook up. The orange & black is off the CD box. I did not use the white wire from the 10-pin harness. And I'm unsure of the fuel pressure, as I don't have a gauge.

  5. #15
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    Doesn't the MSD 6420 have a white wire? I'd connect the white wire from the MSD box to the 10-pin connector Sniper harness. Is your rev limiter disabled on your 6420 if not disable it. These are two pretty easy things to do and I would try first.
    Last edited by RPnova; 03-25-2019 at 04:53 PM.

  6. #16

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    You're correct, it does. I will try connecting the white wire from the MSD to the Sniper harness. I'm just confused as to what would cause this. As everything worked perfect before.
    I still don't know how I would go about bypassing the MSD box.

  7. #17
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    Please disregard bypassing the MSD box. How long did it run well for?

  8. #18

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    At least 500 miles. Aside from getting another MSD box, I don't know what else to try.

  9. #19

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    Can you disconnect your dash tach in the remote chance that it's affecting the tach input to the Sniper?

  10. #20
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    You really should verify what your fuel pressure is at and have a gauge on the engine. This is a necessity in my opinion. Let us know if there is any changes when you hook up the white wire to the Sniper. Before you buy a new MSD box, I'd try another ignition coil, maybe that went bad.

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