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Thread: Verifying Timing Issue

  1. #1

    Default Verifying Timing Issue

    Having issues verifying timing on my car. Recently switched from Megasquirt to a Dominator EFI. Car is a '68 Camaro twin 66mm turbos on E85 58x 6.0L with rods & pistons. I set TDC of #1 cylinder and set the Static Timing to 20°. I’m getting an idle surge at any RPM I set it at and the timing fluctuates up & down. The timing advances when RPM goes up and retards when it goes down at idle. Then when I rev the engine it still fluctuates. I’ve changed the crank sensor, checked voltage at the plug, turned the engine over and made sure the reluctor wasn't off. I’ve done the standard 58x ignition setting, did Custom setting with Inductive Delay from 10-150 usec with not much change. It gets better around 100 usec, but still fluctuates a few degrees up & down. Any ideas where to start or what to do? Thanks for any response!

  2. #2
    Join Date
    Dec 2009
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    Connecticut
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    Default

    That seems like the Idle Spark control during the idle Ramp Down parameters (Idle ICF - EFI software). The Idle Spark control varies the ignition timing to help stabilize the idle RPM. It can be temporarily disabled (Idle ICF) when viewing the idle timing with a timing light. Also, the Base Fuel Table should not be totally flat (except in the Fuel Graph); meaning you can't have the same numbers in the idle area. Unlike the Base Timing Table & Target A/F Ratio Table, which should be flat in the idle area.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crank & rods, forged pistons, Trick Flow T/W 11R 205 CNC comp ported heads, 12:1 comp ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI comp ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM C6 converter, B&M Hammer shifter, Stifflers transmission 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

    Default

    I've also tried disabling the Idle ICF with no luck. Once up to temperature, Closed Loop is only compensating 0-1% at idle. All of this is happening while the Static Timing is set, so I would think the timing wouldn’t move at all regardless if the idle is surging or not?
    Last edited by TwinTurbo68; 06-22-2022 at 09:57 AM.

  4. #4

    Default

    Are you disabling the Idle Spark control?

  5. #5

    Default

    Yea I’ve done both. Disabled the Idle Spark control and not, with no difference. But it was my understanding that with the Static Timing enabled, it would override all of the timing modifiers?

  6. #6
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    Default

    Yes, that's true. The Static Timing Set disables the Idle Spark control.

  7. #7

    Default

    It just seems like something is still enabled that's not locking the timing down. If the idle wouldn’t surge when I enable the Static Timing I think it'd be really close. I’m going to try and mess with it tomorrow and see if I can get the idle surge to go away during the Static Timing check. I also spoke with Holley tech who asked me to redo the ECU firmware update, which I did, and to check the connections to the crank sensor and the “shielding” on the crank sensor at the plug at the Dominator. Everything looked fine to me.

  8. #8
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    Originally Posted by Danny Cabral
    "Enable Static Timing Set" Discrepancy:
    I don't recommend using the Enable Static Timing Set to check the Cranking Timing (fuel injector harness temporarily disconnected). Sometimes (although a rare occurrence) enabling the Static Timing Set indicates the timing isn't synchronized at idle; even though the idle timing has just been physically synchronized (by turning the distributor or adjusting the crank sensor). This is usually due to the trigger wheel being off a little bit, and/or an inaccurate EFI software setting in Ignition Parameters. Either way, it's an installation error or a user EFI software setting error. Example: I once helped a Holley DIS user who had the 60-2 trigger wheel off a tooth or two. This caused the "TDC Tooth Number" (in the EFI software) to be inaccurate, which resulted in a "Enable Static Timing Set" discrepancy (at idle) when used. Once corrected, the "Enable Static Timing Set" matched the idle timing when enabled & disabled.

    This procedure is foolproof and actually confirms itself:
    1st, temporarily disable the Idle Spark control (Idle ICF), and synchronize the timing at idle. (Ensure all timing modifiers are inactive.)
    2nd, activate the Enable Static Timing Set, and confirm the idle timing is still synchronized. (I use a static value of 25° or 30°.)
    3rd, momentarily rev the engine to check timing synchronization at higher RPM, using the Inductive Delay. (Adjust as necessary.)
    4th, disable the Enable Static Timing Set and enable the Idle Spark control.
    Again, this is the same procedure outlined in this timing synchronization tech page (LINK).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crank & rods, forged pistons, Trick Flow T/W 11R 205 CNC comp ported heads, 12:1 comp ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI comp ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM C6 converter, B&M Hammer shifter, Stifflers transmission 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.

  9. #9

    Default

    This sounds like the issue. I’ll try it and report back. Thank you!

  10. #10

    Default

    Just an update. It is fixed. Ended up being the dial back timing light causing fluctuation when I put a certain timing number in the light. It'd get worse with higher timing values. When the light was zeroed it was dead on. Just had to make adjustments to the timing mark on my balancer and everything works as it should.

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