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Thread: Holley DIS & Sequential EFI Upgrade

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    Join Date
    Dec 2009

    Default Holley DIS & Sequential EFI Upgrade

    I recently converted to multi-port fuel injection, then to a custom 60-2 crank trigger kit. I liked the idea of getting rid of my CD ignition box, single coil, distributor & ignition module, so I upgraded to DIS (Distributorless Ignition System). Holley's DIS Kit outputs more spark energy than high-power single racing coils (for forced-induction, nitrous oxide or high compression engines). I fabricated a custom stainless steel plate to mount the DIS coil pack but it's hardly noticeable in the picture. (Detailed Crank Trigger/DIS Conversion Information & Reasoning)! (Distributor vs. DIS/CNP/COP Ignition Timing Difference & Feel)

    After a successful test run with DIS, I decided, what remained of my Mallory Hall-Effect EFI billet distributor (#9556704), needed to serve more purpose than just an oil pump drive. So I converted the distributor to a Hall-Effect "cam sync unit" (for sequential EFI operation), by removing seven of the eight shutter blades, and fabricating a aluminum plate to cap-off what was left of my previous distributor. I later upgraded the digital vane sensor to a Cherry VN101504 (6" x 24 AWG, 3-wire harness & -40°F − 302°F operating temperature). I used the MSD 34019 Super Conductor bulk wire roll and reused all my plug boots. The bulk ignition wire & terminal kit options are available separately (LINK - Page 3 & 4).

    My engine definitely seems to run a little smoother under sequential EFI control BUT nothing very significant.
    The power & driveability of my 508 BBF is just incredible. Modern EFI simply makes this truck a pleasure to drive.
    Here are two pictures of the DIS coil pack and my cam sync/oil pump drive unit:

    While I was at it, I made a nice adjustable spark plug wire hold-down to support the center span of wires (due to the missing distributor cap, rotor & adapter):

    Autotrend EFI sells this cap to cover an Accel dual sync distributor and
    Mallory/Edelbrock Hall-Effect EFI distributors when it's converted to DIS.
    This allows you to retain that raised lip on the housing (I milled mine off):
    Click image for larger version. 

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    Quote Originally Posted by Danny Cabral
    Holley's waste-spark DIS system gets its signal from the two missing teeth on the 60-2 trigger wheel. It's "waste-spark" because the two missing teeth send the TDC signal every time #1 cylinder is up (near TDC of compression stroke and near TDC of exhaust stroke). It doesn't know when the #1 cylinder is ONLY on the compression stroke, hence the need for a cam sync sensor for sequential use. If you don't need or want sequential injection, then you just need an oil pump drive plug. In other words, the two missing teeth (60-2 trigger wheel) are only for DIS ignition and the cam sync sensor is only for sequential fuel injection. If you're not using the 60-2 crank trigger with Holley's DIS, then a cam sync sensor must be used (sequentially injected or not).

    • Another advantage to using a 60-2 crank trigger kit with sequential injection & waste-spark DIS, is the ability to run the engine solely off of it, if the cam sync sensor fails. If you have a laptop computer* with you, enter the Ignition Parameters and change the Cam Sensor type to "Not Used" (non-sequential mode), and continue on your way. A nice emergency capability, that's not possible with a conventional 4x crank trigger (such as an MSD Flying Magnet kit).
    * FYI: The 3.5" & 5.7" LCD Touchscreens can also change Global Folders (create a non-sequential emergency GF), by storing them on the SD Card. And now the Digital Dash is also capable of storing/changing Global Files, except it's stored on a USB flash drive.

    • Also, an inductive ignition system's coils (Holley DIS) will not have the same visual spark intensity as a CD ignition because they only provide the required voltage to jump the spark plug gap...but this is accomplished with over three times the spark duration. Read this webpage tutorial for more detailed information:

    Typical Holley DIS Custom Ignition Parameters:
    Ignition Type ........ ― "Custom"
    Crank Sensor Type ― "60-2"
    Sensor Type ........ ― "Digital Falling"
    Inductive Delay .... ― "adjusted per application" (← Synchronization info.)
    Timing Offset ....... ― "0°"
    TDC Tooth Number ― "9, 10, 11 or 12"
    Cam Sensor Type . ― "Single Pulse" (← If sequentially injected.)
    Sensor Type ........ ― "Digital Falling" (← If sequentially injected.)
    Output Setup Type ― "DIS Waste Fire"
    Dwell Time .......... ― "1.8 msec" (early coils) "2.4 msec" (late coils)
    Quote Originally Posted by Danny Cabral
    • Before the initial start, disconnect the fuel injector harness and verify at least, the first four cylinders in the firing order using a timing light.
    If your cylinders are firing in 90° intervals BUT in the wrong sequence, the coil harness is connected wrong (at the ECU or at the coil packs).
    Hopefully you have a fully degreed balancer or at least markings every 90°:
    1st cylinder, in firing order, should fire at 0° (or 15° - add whatever your cranking timing is)
    2nd cylinder, in firing order, should fire at 270° (or 285° - cranking timing added)
    3rd cylinder, in firing order, should fire at 180° (or 195° - cranking timing added)
    4th cylinder, in firing order, should fire at 90° (or 105° - cranking timing added)
    5th cylinder, in firing order, should fire at 0° (or 15° - cranking timing added)
    6th cylinder, in firing order, should fire at 270° (or 285° - cranking timing added)
    7th cylinder, in firing order, should fire at 180° (or 195° - cranking timing added)
    8th cylinder, in firing order, should fire at 90° (or 105° - cranking timing added)

    • Troubleshooting Holley's DIS smart coils, with a multimeter (ECU triggering):
    Think of the coils as a relay, in respect to wiring and how they're triggered.
    They have a main +12V & chassis ground, and an ECU triggered power & ground.
    The ECU ground trigger (B14) is common to all the coils, and tied together in the harness.
    The ECU triggered power (B21, B22, B23, B24, B15, B16, B17, B18) is obviously individually wired to each coil.
    Holley's 8-cylinder DIS only uses four of the eight ECU triggers (waste-spark); B21 is always for #1. (8-cylinder CNP/COP uses all eight.)
    Using your multimeter, check for a pulsed 5 volt trigger when cranking the engine.

    You may need to use the Peak Hold function on some multimeters. Switch off the Auto setting on the multimeter.
    Also, ensure the two high current spade connectors between each coil & module, make good tight contact (Link).
    Quote Originally Posted by Danny Cabral
    • Excellent Waste-Spark DIS tutorial: (Autolite Technical Video)
    After watching this Waste-Spark DIS Tech Video above, five points really stand out:

    1) The waste-spark DIS ignition must output greater spark energy and saturation time (duration), through its long secondary circuit (two spark plugs). So a vehicle with waste-spark DIS must have a good alternator & charging system to consistently power the ignition system.
    2) Each waste-spark coil always fires one spark plug in the conventional forward direction, and its companion spark plug in the reverse direction. So the engine block and cylinder heads must be very well grounded. For this reason, platinum or iridium spark plugs (not for heavy N2O use due to fine wire design) should be used, because they conduct electricity better and require less voltage to fire the spark. Iridium spark plugs are also 6 times harder, 8 times stronger and have a 1200°F higher melting point than platinum.
    3) The waste-spark DIS ignition, simultaneously fires a pair of cylinders; one near TDC of the compression stroke ("Event Cylinder") and near TDC of the exhaust stroke ("Waste Cylinder"). The exhaust stroke spark (although less energy) isn't actually wasted, because any unburnt fuel during the initial combustion event, will be burned on the exhaust stroke. This also improves exhaust emissions. For this same reason, I feel one must be especially scrutinous when reading spark plugs for performance tuning purposes (due to the second ignition event).
    4) The amount of cylinder pressure & greater electrical resistance, determines which spark plug gets the majority of the coil's voltage (compression stroke) and which spark plug gets the waste voltage (exhaust stroke). So an engine needs to be in good working order to ensure proper operation of a waste-spark DIS ignition system.
    5) A conventional ignition coil has one end of the secondary winding connected to engine ground. In a DIS ignition system, neither end of the secondary winding is grounded. Instead, each end of a coil's secondary winding is attached to a spark plug. The DIS ignition system wiring is more complex (battery, ground, sensors, ECU, 4 coils, etc.), so its +12V power, ground & wiring connections need to be in very good condition. (Good NGK Tech Document) (Holley EFI DIS Manual)
    Quote Originally Posted by 8.6 Magnetic Crank Pickup - Holley EFI Wiring Manual
    If running a magnetic pickup, either a crank trigger or a distributor: To run just a magnetic pickup crank input and no camshaft input, PN 558-303 should be purchased. If a cam sync input will be used as well, it is recommended to use PN 558-306 which will contain wiring for both the crank and cam sensor inputs. It is critical that properly installed shielded and grounded cable is used when using a magnetic pickup, or it is likely that EMI will disturb the crankshaft signal. Both PN 558-303 and 558-306 come with the proper cabling. It must be installed properly as well. Make sure that the shield is properly grounded which requires it being grounded at the ECU with that ground maintained through the ignition adapter connection.
    FYI: The MSD 2-pin connector (LINK) is a TE Connectivity, Commercial Mate-N-Lok, Free-Hanging #1-480318-9 (Plug Housing) & #1-480319-9 (Cap Housing).
    Note: The end user must supply the proper connectors/terminals for the crankshaft & camshaft sensors they choose to use with their Holley EFI system.
    Note: If using an MSD Flying Magnet 4x crank trigger kit, it's highly recommended to use Holley's 554-118 Hall-Effect replacement (direct-fit) crank sensor.
    Quote Originally Posted by Danny Cabral
    • If using a crank trigger kit, this link informs how to modify a
    distributor's magnetic pickup reluctor for cam sync operation: (Modification Instructions) (Extra Reluctor To Modify)
    This involves removing 7 of the 8 reluctor teeth, and locking-out the timing advance mechanism.
    You can use a Hall-Effect "geartooth" type sensor (LINK) with the distributor's reluctor; no magnet installation.

    However, for DIS & CNP/COP, the conversion is much easier than what's outlined in the link above:
    There's no need to modify the reluctor with a setscrew (so it can rotate independently on the shaft).
    This adjustability isn't necessary because the cap & rotor are eliminated, so there's no #1 terminal rotor phasing.
    Simply cut off any 7 of the 8 reluctor teeth, and fabricate a cover to take the place of the discarded cap, adapter & rotor.

    • Custom sensors and/or harnesses:
    1) The ECU already has the pull-up resistor for sinking output (open collector) sensors inside, so don't add anything.
    2) The ECU already has the shield (drain) wire connection/pin grounded inside, so don't ground it at the sensor end. (Shielded Wiring - look for "drain wire" on page 2 & 3.)
    Think of the shield wire as an antenna pointing to the sensor; it's only supposed to be grounded at the ECU end.
    Quote Originally Posted by Electromotive Engine Controls
    • How does it compare to a CD (Capacitor Discharge) Ignition?
    According to the BOSCH Automotive Handbook 3rd Edition:
    Page 460… "The major advantage of the CDI is that it generally remains impervious to electrical shunts in the high voltage ignition circuit, especially those due to spark-plug contamination. For many applications the spark duration of 0.1 … 0.3 ms is too brief to ensure that the air-fuel mixture will ignite reliably. Thus CDI is only designed for specific types of engine, and today its use is restricted to a few applications only, as transistorized ignition systems have virtually the same performance. CDI is not suited for aftermarket installations." (CDI vs. Inductive Ignition)
    Quote Originally Posted by Motec - About Ignition Systems
    Inductive Ignition vs. Capacitor Discharge Ignition
    In an inductive ignition system, the coil is charged at battery voltage for a period of time—known as 'dwell time'—prior to firing. The dwell or charge time is controlled by the ECU and should match the coil being used in order to not over or under charge. Undercharging reduces available spark energy, while overcharging can cause overheating of the coil and/or ignition module. Inductive ignition systems produce a spark, at a lower voltage with a longer duration compared to capacitor discharge ignition systems.

    A CDI, Capacitor Discharge Ignition system is charging constantly and sends a large voltage charge (380–450 V) to the coil. The spark produced is extremely short in duration and at a much higher voltage than an inductive setup. Note that inductive coils should not be used with a CDI system; CDI compatible coils are required.

    There are three main engine running characteristics to consider:

    • High Cylinder Pressures
      Generally, higher cylinder pressures require more voltage to initiate a spark. Boosted or nitrous injected engines create tremendous cylinder pressures that increase resistance to lighting the ignition spark. CDI systems are most often used on these engines.
    • High RPM
      The time available to charge the coil in an inductive system reduces at higher RPM. If the time available is shorter than the time required for a full charge, coil power and, as a result, performance will be reduced. A CDI system might be required.
    • Lean Mixtures
      The shorter spark duration in CDI systems might not be sufficient to ignite enough of the mixture to propagate the flame front through the cylinder. Inductive ignition will perform better in this setup.

    Most vehicles, including high performance road and race applications use an inductive ignition system. Generally, if your engine can run correctly on an inductive setup, it is better to leave it that way and install a CDI system only when your engine, due to high RPM or cylinder pressure, requires that you do so.
    Quote Originally Posted by Gill Instruments
    Inductive Ignition
    Inductive ignition systems have existed since 1908, developed by Charles Kettering who also developed the first practical engine driven generator.
    The design has been improved over the years but the most significant recent development has been the introduction of Insulated Gate Bipolar Transistors (IGBT); these have allowed the design of extremely accurate, high spark energy inductive ignition systems. A single operation is carried out by a transistor turning on the current to the ignition coils primary winding. This charging stores energy in the coils magnetic circuit. The current is then switched off. As the magnetic field begins to collapse the coil tries to resist the drop in current causing the voltage in the secondary winding to rise rapidly, this high voltage breaks down the air/fuel mixture in the spark gap allowing a spark to pass causing ignition of the air/fuel mixture.

    The most significant advantage of inductive ignition systems is that inductive coils are generally more efficient than capacitive discharge coils as they can provide longer spark duration that can ensure complete combustion, especially on lean burn and turbo charged engines. The ability to provide longer spark duration is because inductive coils only provide enough energy to cross the spark gap; the remaining energy from the ignition coil is used to maintain the spark. Capacitive discharge coils release almost all of their energy instantaneously, therefore considerably reducing the amount of energy available to maintain the spark.

    With inductive ignition systems more energy can be delivered to the secondary winding of the coil than in a capacitive ignition system. In fact, with the same power supply current draw, up to five times more energy can be delivered to the secondary winding of an inductive ignition coil than to a capacitive discharge coil. Typically a capacitive discharge system will deliver a maximum of 10 millijoules of energy compared to an inductive ignition system delivering more like 50 millijoules of energy and potentially in excess of 100 millijoules. This large difference in supplied energies will mean an inductive system can provide spark duration of 2000 microseconds or more in a single spark, compared to 600 microseconds for a capacitive system.

    With inductive ignition systems the time taken to charge the ignition coil is called the Dwell. This dwell can be increased or decreased for differing engine applications. If longer spark duration is required to improve combustion of lean mixtures or engines with large cylinders the dwell time is increased, inputting more energy into the primary coil. Dwell time is decreased when there is more than enough spark energy to combust the mixture, this decrease will reduce spark plug wear, therefore increase spark plug life.
    The high energy and long, programmable spark durations are a considerable advantage since they provide better ignition of lean or non-homogeneous air/fuel mixtures. In many cases engines that are unable to meet emission standards with capacitive discharge systems can be bought into compliance with electronic inductive ignition systems such as those manufactured by Gill Instruments.

    Capacitor Discharge Ignition
    Electronic capacitor discharge ignition (CDI) systems have been common on large industrial engines because the technology has been in use since the 1960's.
    An advantage of the capacitor discharge ignition system is that the energy storage and the voltage 'step up' functions are accomplished by separate circuit elements allowing each one to be optimized for its job. Capacitive discharge ignition systems work by storing energy in an external capacitor, which is then discharged into the ignition coil primary winding when required. This rate of discharge is much higher than that found in inductive systems, and causes a corresponding increase in the rate of voltage rise in the secondary coil winding. This faster voltage rise in the secondary winding creates a spark that can allow combustion in an engine that has excess oil or an over rich fuel air mixture in the combustion chamber. The high initial spark voltage avoids leakage across the spark plug insulator and electrodes caused by fouling, but leaves much less energy available for a sufficiently long spark duration; this may not be sufficient for complete combustion in a lean burn turbocharged engine resulting in misfiring and high exhaust emissions.

    The high voltage power supply required for a capacitor discharge system can be a disadvantage, as this supply provides the power for all ignition firings and is liable to failure.
    Ignition in lean fuel mixtures by capacitor discharge systems can sometimes only be accomplished by the use of multi-spark ignition, where the ignition system duplicates the prolonged spark of inductive spark systems by sparking a number of times during the cycle. This adds greater stress onto the high-tension leads and can cause considerable spark plug wear and possible failure.

    CDI vs. Inductive Ignition
    The term 'CDI' is often, incorrectly, used to describe electronic ignition systems. Most modern ignition systems are actually Inductive Ignition systems for good reason, especially when using lean burn fuel mixtures. Inductive ignition systems can provide prolonged spark duration; resulting in more reliable and a cleaner burn in modern lean burn engines.

    Capacitive discharge systems may have advantage in older 4-stroke engines, an engine running beyond its service life, or a cheap 2-stroke engine. These engines will be running an oil rich / fuel rich mixture, which may cause fouling of the spark plug gap. The higher initial discharge of a CDI system may be able to 'burn' off these deposits better than a comparative inductive ignition system.

    Ignition Coils
    Ignition coils are used to step up the voltage of the engines primary circuit of the 12 - 24 volt range to 20,000 to 40,000 volt range [higher for performance coils]. The increased voltage is required for the current to jump the spark gap in spark plugs, producing the ignition of the air/fuel mixture. The increase of the voltage is matched by a proportionate decrease in current. At its most basic an ignition coil is made up of a primary winding, a secondary winding and a laminated core.

    The secondary winding is wound with considerably more turns than the primary winding. The resulting difference in number of turns is proportional to the step up in voltage. An inductive ignition system will charge the primary winding with generally 12 volts, when the current is removed a large EMF is generated in the secondary winding of up to 40,000 volts [higher for performance coils], more than enough to jump across a spark gap. In practice ignition coils will have some extra components but are in operation practically the same.
    (Electronic Technology Explained)
    Quote Originally Posted by Danny Cabral
    • Just a general FYI:
    "Spark plug reading" for performance tuning purposes is not the
    same as "spark plug inspection" for general maintenance/repair.
    There's a significant difference between the two.
    Last edited by Danny Cabral; 08-09-2012 at 11:26 AM. Reason: additional information
    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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