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Thread: Spark Advance While Cranking

  1. #1

    Default Spark Advance While Cranking

    I have a recently installed Terminator and Dual Sync on my stroked 302 Ford (331 ci + manual transmission). System was installed by a shop with a good reputation and the system was tuned on a dyno. I have only a few hours on the setup and it is still Learning, but seems to be running more smoothly across the board. One area that needs attention is starting. The crossover RPM is set to 400. The Cranking Timing advance is set to 10°. However, while cranking, timing starts at 10° then jumps to 25° as soon as an RPM signal is synced. This occurs at a cranking RPM of about 135 RPM. Then after a delay of less then 2 seconds the timing advance jumps to 33°. This seems to occur if the 400 RPM crossover RPM is reached or not, but I'm only observing from the handheld.

    It is my understanding that the ECU's control is somewhat limited until the cranking/running crossover RPM is reached. How is it that the timing could skip from 10° to 25° (and maybe to 33°) before the crossover RPM is reached? Here's a video of the handheld during cranking:

  2. #2
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    Quote Originally Posted by gump View Post
    How is it that the timing could skip from 10° to 25° (and maybe to 33°) before the crossover RPM is reached?
    You tell me. My Ford engine doesn't transmit a cranking RPM signal like that. This is what you need to investigate; troubleshoot why your crank sensor unit isn't transmitting a consistent signal. Troubleshoot the crank sensor, wiring, reference voltage & ground, reluctor, alignment, air gap (LINK), radial run-out problems (LINK), etc.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  3. #3

    Default

    Thanks. Crank signal is coming from the Holley Dual Sync distributor. Is there anything physical that can be inspected/adjusted inside the Dual Sync? What should the cranking RPM signal look like?

  4. #4
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    Quote Originally Posted by gump View Post
    What should the cranking RPM signal look like?
    The cranking RPM should be consistently at 10° or whatever you have it programmed at. Charge your battery and check your engine grounding (LINK).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  5. #5

    Default

    I'm sorry. I'm confused. You said: My Ford engine doesn't transmit a cranking RPM signal like that. Then in answer to my question What should the cranking RPM signal look like? You said: The cranking RPM should be consistently at 10° or whatever you have it programmed at.

    It seems we're talking about two things: The Engine RPM signal and the Ignition Timing Degrees. The RPM signal is measured from the crank position sensor, which, in my case is in the Dual Sync distributor. The Ignition Timing Degrees is commanded by the ECU. Is that right? I suspected that the Ignition Timing Degrees during cranking should not bounce around. I interpreted from your first comment that the RPM signal didn't look right to you. That's why I asked what it should look like (the RPM signal).

    I think what you're saying is that there is likely an out of range input occurring that is causing the ECU to advance timing during cranking and that I should start with grounds, reference voltages, etc. What I wanted to clarify is what you thought looked odd/irregular about the RPM signal.

  6. #6
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    Quote Originally Posted by gump View Post
    The Ignition Timing Degrees is commanded by the ECU. Is that right?
    Yes, of course.

    I suspected that the Ignition Timing Degrees during cranking should not bounce around.
    Agreed, that's all I was stating.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

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