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Thread: Holley Sniper

  1. #1

    Default Holley Sniper

    Hello. I've tried for a couple of months to Coax the Sniper setup to perform.
    Setup was Sniper 650 four injector, HyperSpark Ignition Box, Coil, and distributor. Issues were:
    1) ECU could not find timing signal for #1 cylinder and would fluctuate wildly in search of signal to lock on.

    2) Number one cylinder would not fire, only randomly, causing 200° less cylinder temp and obviously rough idle.

    3) Oxygen Sensor would randomly drop communication with ECU shutting down system

    4) Replaced fuel pump in tank to a 340 LPH with 3/8" lines, yet regulator would only pressurize to 45 lbs.

    Wiring was per instructions and no RFI issues. At this point I stopped, removed all Sniper components and replaced with 670 Holley Carb, HEI Ignition, and MSD Spark box. All previous issues are gone. Engine runs fine.

    I'm reluctant to reinstall the Sniper System at this time due to fact it's running so well. I'm thinking ECU is faulty, but have no clue how to verify individual components as to function and reliability. If anyone out there has the skill to test these components I would like to talk with you. Thank you for your time. Fred

  2. #2

    Default

    Hi & welcome. How do you know for sure you did not have EMI issues? It sure sounds like you had wiring issues of some sort.
    69 Camaro
    400 SBC, ProCharger D1SC
    1.302 60', 5.95@116.4 on pump gas

  3. #3

    Default

    Hello. I use Magnecor 8MM ignition wires (red). Routed and loomed. Sniper wiring was routed from battery right side inner fender, over overflow container. Power directly connected to battery posts. CD box mounted to inner fender right side and coil mounted to cowl over distributer. O2 sensor wire routed at back of motor on right side intake. No wires crossing each other as per instructions.

    This is a 1990 Chevrolet SS454. The TBI wires were eliminated so the only wiring in the engine bay was for the Sniper unit, except for keyed ignition wire. The cooling fans are stand alone with own separate VSS unit. Battery connections are via #2 gauge welding wire to starter and alternator. Engine is grounded to frame, firewall, and directly to negative battery post.

    If there is EMI issue, not sure where or how. Running aluminum intake on cast iron heads. Temp gauge on intake, oil pressure sender mounted low in front on drivers side, alternator wire follows oil pressure wire then terminates at alternator. Fuel relay in stock location and routes along cowl and down to frame on driver side. Personally, I could not find anything which would hint at EMI potential crossing wires. Fred

  4. #4
    Join Date
    Oct 2017
    Location
    Los Angeles
    Posts
    399

    Default

    Do you have any datalogs you can share to rule out EMI?
    1964 Chevy Nova, 383 Stroker, AFR 210 Heads, Ford 9inch w/TrueTrac/3.90 Gears, Powerglide Transmission. www.SoCalStreetCars.com

  5. #5

    Default

    That does sound like very solid wiring and great plug wires. I was getting EMI through the pink +12V trigger wire when I had it wired to the fuse box, exactly like Holley shows in the video. Moving that to a relay with clean power directly from the battery helped as well. If you're certain you're dropping fire to just one cylinder then I'd say send the ECU back and have Holley take a look. They had a few HyperSpark distributor issues too, but much less common than ECU. I assume since you're not dropping a cylinder now with the carb, that it's not a mechanical issue.
    69 Camaro
    400 SBC, ProCharger D1SC
    1.302 60', 5.95@116.4 on pump gas

  6. #6

    Default

    Hello. Never got it running well enough to drive on street.

    You know, that's one thing I did not try, was to use a clean relay for power supply. I want to try reinstalling this winter, just slightly "gun shy" if results are same as before. I'll contact tech support and see if they can verify ECU is working normally. Fred

  7. #7
    Join Date
    Oct 2017
    Location
    Los Angeles
    Posts
    399

    Default

    You do not need to take the car out on the street for a datalog. You can take a datalog with the power on and the engine off for example.
    1964 Chevy Nova, 383 Stroker, AFR 210 Heads, Ford 9inch w/TrueTrac/3.90 Gears, Powerglide Transmission. www.SoCalStreetCars.com

  8. #8

    Default

    If you bought this new, then sending the TB to Holley is the best thing you can do. I sent a couple back for service and they paid the shipping both ways. I had them back in my hands in a week. A call to Holley Tech will get the ball rolling.

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