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Thread: Tach Not Working

  1. #1

    Default Tach Not Working

    Sniper 4150, HyperSpark distributor, coil & ignition. Just swapped over to the Sniper system and my tach isn't working. It was working well prior to the swap on the (-) coil terminal. Now I have it connected to the brown wire off the TB as shown in the manuals. It is a Sun Super Tach II. The instructions are quite clear about not connecting anything to the coil terminals so am I missing something? Thanks!

  2. #2
    Join Date
    Dec 2009
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    Connecticut
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    https://forums.holley.com/showthread...361#post226361 (Holley Sniper EFI Tachometer Wiring Information)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, 36-1 crank trigger, 1x cam sync, 200A 3G alternator, Optima Red battery, R134a A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM converter, B&M Hammer shifter, Stifflers trans crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  3. #3
    Join Date
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    Wheeling, WV
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    You mentioned you're using a CDI box. The tachometer signal comes from the CDI box, not the ECU when using a CDI box.

  4. #4

    Default

    The CDI box instructions (attached) doesn't have any wiring for the tach. I also confirmed that the tach is connected to the brown wire from the throttle body as indicated in the wiring diagrams of the instructions.
    Attached Files Attached Files
    Last edited by Timbick; 07-03-2021 at 08:02 AM.

  5. #5
    Join Date
    Dec 2009
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    Connecticut
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    Well if the Sniper EFI dark brown Tach Output wire doesn't operate your tachometer, then you might need a CDI box that does have that wire/function. See posts #2 & #3.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, 36-1 crank trigger, 1x cam sync, 200A 3G alternator, Optima Red battery, R134a A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM converter, B&M Hammer shifter, Stifflers trans crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  6. #6

    Default

    I apologize, but I'm not following. I read the thread linked above (which sounds like that individual was having wiring issues with a different type of CDI box) as well as all of the instruction manuals that came with each component of the system that I have, and they all indicate wiring the tach to the dark brown wire coming from the throttle body. Did Holley make a mistake in the instructions?

  7. #7
    Join Date
    Dec 2009
    Location
    Connecticut
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    29,048

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    See tachometer output with CDI box: http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual, Pages 29 - Magnetic distributor & 35 - Hall-Effect distributor)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, 36-1 crank trigger, 1x cam sync, 200A 3G alternator, Optima Red battery, R134a A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM converter, B&M Hammer shifter, Stifflers trans crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  8. #8

    Default

    I've read those and I don't have any of those configurations. One thing lacking in Holley's Sniper EFI instructions is anything about the HyperSpark box. Those instructions don't even include the choice to select HyperSpark distributor. Page 17 of this manual shows the brown wire output to drive tach in the 10-pin connector, which is what the instructions for the HyperSpark ignition module says to use.

  9. #9

    Default

    Not all aftermarket parts work with each other. If your Sun tachometer doesn't work with the Holley Sniper, then you might need to buy a Holley tachometer. Or you might need some sort of tach adapter. If you have a buddy who understands electronics, ask him to help. A quick look with a scope will answer the question.

  10. #10

    Default

    My tachometer in my 1977 Ford didn't work either, so I took it to an instrument fella and he converted it, and now works fine on the brown wire.

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