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Thread: Untimed Sequential Injection

  1. #1

    Default Untimed Sequential Injection

    I read all I could find on Untimed Sequential injection so far here & else where. I'm thinking this may work well with my setup (SBC 388, 13 psi, 120 lb/hr injectors, 60-2 crank trigger, MSD 7AL box, MSD distributor just for spark, E85 or 93 unleaded 700 RWHP on 93). My question is how does the computer figure out the Firing Order in relation to firing the injectors, or doesn't it? Also, is there some setup work with it? Any information on the topic would be a great help. Or should I go with Paired or Bank-To-Bank instead? This is a street car, so I'm hoping this will help with driveability.

  2. #2
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    Holley's Untimed Sequential injection strategy still injects once per revolution, but without a cam sync sensor. It still injects fuel in accordance to the engine's firing order (programmed into EFI software), however, without a cam sync sensor, it can't identify #1 cylinder. Holley's Untimed Sequential injection (like full sequential) also has the benefit of good idle quality with large injectors and improved fuel rail pressure balance (pulses); even though it doesn't inject in sequence with each cylinder's intake valve opening.

    Holley EFI systems are capable of four types of injection strategies:
    • Bank-to-Bank ― Fires half the injectors and then the other half every 180 crankshaft degrees (injectors fire once per revolution).
    • Untimed Sequential ― Fires each injector every 90 degrees. But since there is no cam sync signal, it is random which cylinder is first triggered.
    • Paired ― Similar to Bank to Bank, except only two injectors are fired at a time (fires a pair of injectors every 90 crankshaft degrees).
    • Sequential ― Fires the injectors in sequence of engine's firing order (requires cam sync sensor).
    http://forums.holley.com/showthread....amp-Paired-EFI (Holley EFI Injection Strategies)
    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

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    Thanks so that's how I thought it works, but wanted to make sure I was not missing anything. Next question, fuel Injector End Angle table. How does this impact the injection strategy when it's enabled and all the correct information is entered? Also, what does the "injector auto phasing" do, and how will this impact Untimed Sequential injection or the others. Again, thanks for all your help. Your customer service knowledge & help in general, has not only helped me to understand what it is I'm doing, why I'm changing things it, how should impact the system. But also a few of my friends have switched to Holley HP & Dominator systems after hearing my experiences with it. You liberated me from the carburetors. LOL!

    Next question my MSD distributor. I'm using has a unused magnetic pickup in it. Is there any way to modify it to use it for a single pulse cam sync signal? I'm a mold maker by trade, and can pretty much fabricate anything myself with the right information. I do use a belt drive on the cam, but the water pump & packaging of the motor prevent me from using the Holley sensor kit there. ('92 Corvette packed together like 10 pounds of angry potatoes in a 5 pound sack.)
    Last edited by russeko8; 08-18-2016 at 06:12 PM.

  4. #4
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    Quote Originally Posted by russeko8 View Post
    Next question, fuel Injector End Angle table. How does this impact the injection strategy when it's enabled and all the correct information is entered? Also, what does the "injector auto phasing" do...
    This should answer all your Injector End Angle questions:
    http://forums.holley.com/showthread....-Phasing-Table (Injector End Angle Phasing Table)

    For more Injector End Angle information: Open the Holley EFI software & "Help" Contents (top Toolbar), and read the "Injector Phasing Instructions".

    EFI Software Help Information/Instructions:
    ‒ On the top Toolbar, click "Help" & "Contents". This opens all Help topics.
    ‒ When navigating the software, click "Help ?", drag it to any parameter and click again.
    ..This automatically opens the definitions for that specific parameter.
    ‒ Tuning information can be read by clicking the F1 key, when you're viewing any screen.
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual)

    Next question my MSD distributor. I'm using has a unused magnetic pickup in it. Is there any way to modify it to use it for a single pulse cam sync signal?
    This should answer all your crank/cam sensor questions:
    http://forums.holley.com/showthread....6274#post56274 (Related Forum Thread)
    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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