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Thread: Sniper Erratic Timing

  1. #1

    Default Sniper Erratic Timing

    Trying to enable timing control on my Sniper. Was running great with the Pertronix and no timing control, had the fuel sorted so thought I'd move onto the timing control.
    MSD distributor, locked out with adjustable rotor. Installed as per Holley Sniper instructions. Blaster 2 coil, no box.
    Confirmed static timing is fine, 15° static on the handheld matches 15° static on the balancer.
    Rotor phasing is fine. Good sweep from about 10° to 36°.
    Timing is only erratic at idle, as soon as I open the throttle it advances to cruise and stabilizes, but then takes forever to return to idle.
    All settings in the handheld are as per factory settings except reference angle is 50 to allow me 40 timing (factory setting was 45)
    Seems to idle fine during static check and it evens out at 15°, but as soon as you hand the ECU control it flips out and won't idle.
    Timing jumps from 7° to 30°, idle jumps around from 800 RPM (target) to 2000 RPM & back.
    No vacuum leaks, double checked wiring it is as per Holley instructions including the coil driver.
    Any suggestions? I'm lost here. See datalog below, green is timing.
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  2. #2
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    Default

    Quote Originally Posted by 91chevota View Post
    Timing is only erratic at idle, as soon as I open the throttle it advances to cruise and stabilizes, but then takes forever to return to idle.
    That's normal. That's the Idle Spark control varying the ignition timing to stabilize the idle.
    http://documents.holley.com/199r11031r.pdf (Holley Sniper EFI Instruction Manual - "Idle Spark", Page 31)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

    Default

    The idle isn't stable. Idle is from 700 to 2000 RPM jumping all over the place, and AFRs constantly jump from lean to rich. Runs really rough and smells rich. The idle doesn't actually vary by that much, but it does hunt around from about 700 to 1200.
    Won't return to idle when the throttle is opened.

  4. #4
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    I said the timing fluctuation at idle is normal, not the unstable idle. You claimed you had the "fuel sorted", so you moved onto ECU timing control. So if it was "running great" before, I'd look at the timing parameters. Also, look at the RPM channel data, does it ever display RPM Error?
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

    Default

    No worries Danny. I tried disabling Idle Spark for that very reason. It helped but only marginally. With it disabled, it just fluctuates from idle to cruise timing and back with maybe a quick stop halfway. First thought I had about that, was if the RPM signal jumped high enough it would try to go into cruise timing? But every time it jumps to cruise timing, the RPM is still only around 1200 which is still too low. Which timing parameters should I be looking at in particular? No, haven't seen an error on RPM channel. Just constantly bounces around quite quickly.

  6. #6
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    Quote Originally Posted by 91chevota View Post
    No, haven't seen an error on RPM channel. Just constantly bounces around quite quickly.
    This doesn't seem right. You said it was "running great" before you installed the locked out MSD distributor with the adjustable/phaseable rotor. So this must be something to do with it. Try removing the adjustable/phaseable rotor, and idle it with the original rotor. It has caused problems for some users.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #7

    Default

    Will do. Out at the moment, I'll set the adjustable rotor at zero when I get home and see what it does.

  8. #8
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    No, I'd test it with the original rotor. It wasn't the phasing causing the problem, it was the adjustable/phaseable rotor itself.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. #9

    Default

    OK, I'll do that then. Any idea what the issue is the phaseable rotor? Seems weird for it to have an issue of it's just a contact and a ribbon to distribute power to the posts?

  10. #10
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    I wish we all knew why. If I had that distributor and both rotors in my possession, I think I could determine the problem.
    Honestly, I wouldn't use a magnetic pickup distributor. If purchasing a distributor, I would buy the Holley Dual Sync Distributor.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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