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Thread: Holley HP EFI - Which Ignition Setup?

  1. #21

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    Danny, I read your instructions here:
    http://forums.holley.com/showthread....7990#post47990 (Related Forum Post - Wiring To Pin B20, "EST +12V Output)
    But just want to verify a few things. The CAM sensor AND the CRANK trigger sensor are both going to pin E of the ignition harness for clean +12V? (So, basically a splice coming out of PIN E to both sensors)? So basically Pin B20 on the main ECU connector is empty from the factory? And we are simply supplying the +12V to it by doing the splice you mention?

    Here's what you wrote in that previous post:
    There's a factory splice on the red/white switched +12V wire, as illustrated in the Holley EFI Wiring Manual (wiring schematics - Section 13 Wiring Appendix). This splice is located a few inches away from the system fuse. Switched +12V power is routed to the P1A ECU connector (pin A10) and to the 10-pin Ignition harness connector (pin E). I simply cut the wire (Which wire, the mentioned red/white wire with the splice? OR the wire going to PIN E on the ignition harness?) leading to the Ignition harness connector (at the splice), and lengthened it to the P1B ECU connector (pin B20 - EST +12V Output). Now pin E at the Ignition harness connector, is a clean, ECU regulated +12V for ignition crank & cam sensors.

    Does A10 still have +12V, or is it now dead? After looking at the wiring for some time, what I think I see is red/white coming straight in from key on power source outside the harness that wire is spliced into 2 red/white wires. One going to A10 and the other going to the ignition E Pin. The ECU would not be in control of that +12V right? If that's the case, why is Pin E as it stands now not a good choice to drive the +12V ignition? Confused...
    Last edited by Velocity540; 11-17-2014 at 04:04 PM.

  2. #22
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    Quote Originally Posted by Velocity540 View Post
    The CAM sensor AND the CRANK trigger sensor are both going to pin E of the ignition harness for clean +12V? (So, basically a splice coming out of PIN E to both sensors)?
    Yes. Although it's only as clean as your Switched +12V power source (ignition switch), unless you perform the pin B20 wiring modification.

    So basically Pin B20 on the main ECU connector is empty from the factory?
    Yes. That's why I stated, "It's quick & easy, and we're only installing a short section of wire (about 12" long) with an ECU mating terminal (Link)."

    And we are simply suppling the +12V to it by doing the splice you mention?
    No. Pin B20 is supplying a clean, ECU regulated +12V. You're taking +12V from it, not feeding it +12V.

    I simply cut the wire (Which wire, the mentioned red/white wire with the splice? OR the wire going to PIN E on the ignition harness?) leading to the Ignition harness connector (at the splice), and lengthened it to the P1B ECU connector (pin B20 - EST +12V Output).
    You wrote your question (in bold print) right before the answer in the sentence.

    Does A10 still have +12V, or is it now dead?
    Of course it still has +12V Switched power. The ECU needs this circuit to remain untampered with.

    After looking at the wiring for some time, what I think I see is red/white coming straight in from key on power source outside the harness that wire is spliced into 2 red/white wires. One going to A10 and the other going to the ignition E Pin.
    Yes. Leave the circuit from +12V Switched power, leading to pin A10 (P1A ECU connector) in tact.

    The ECU would not be in control of that +12V right?
    The ECU receives +12V Switched power at pin A10 (from the ignition switch), it doesn't control it; the ignition switch does.

    If that's the case, why is Pin E as it stands now not a good choice to drive the +12V ignition?
    Because the Switched power (from ignition switch) is not a clean, ECU regulated +12V power supply.

    Confused...
    I was very explicit in that forum post (Link). I think you just need to read it again.
    Also, that simple wiring modification is not always necessary. Only do it if you need to.
    https://www.holley.com/document/tech...10555rev16.pdf (Holley EFI Wiring Manual - Figure 11 & 12, Page 20 & 21)
    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. #23

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    Quote Originally Posted by Danny Cabral View Post
    Yes. Although it's only as clean as your Switched +12V power source (ignition switch), unless you perform the pin B20 wiring modification.

    Yes. That's why I stated, "It's quick & easy, and we're only installing a short section of wire (about 12" long) with an ECU mating terminal (Link)."

    No. Pin B20 is supplying a clean, ECU regulated +12V. You're taking +12V from it, not feeding it +12V.

    You wrote your question (in bold print) right before the answer in the sentence.

    Of course it still has +12V Switched power. The ECU needs this circuit to remain untampered with.

    Yes. Leave the circuit leading to pin A10 (ECU connector) in tact.

    The ECU receives +12V Switched power at pin A10 (from the ignition switch), it doesn't control it; the ignition switch does.

    Because the Switched power (from ignition switch) is not a clean, ECU regulated +12V power supply.

    I was very explicit in that forum post (Link). I think you just need to read it again.
    Also, that simple wiring modification is not always necessary. Only do it if you need to.
    https://www.holley.com/document/tech...10555rev16.pdf (Holley EFI Wiring Manual - Figure 11 & 12, Page 20 & 21)
    Got ya. Take the red/white wire after the splice that leads to Pin E, and make that wire go to B20.
    Clear as day. Splice Pin E into 2 separate wires, feeding each sensor with clean +12V power.

    Quote Originally Posted by Danny Cabral View Post
    Also, that simple wiring modification is not always necessary. Only do it if you need to.
    I'm wondering if this is even needed in my particular application. Very basic setup.

  4. #24
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    Quote Originally Posted by Velocity540 View Post
    I'm wondering if this is even needed in my particular application. Very basic setup.
    Only you can answer that question. I consider my EFI system very typical, but I needed that simple wiring modification.
    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. #25

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    Quote Originally Posted by Danny Cabral View Post
    Only you can answer that question. I consider my EFI system very typical, but I needed that simple wiring modification.
    Thanks Danny, we are all wired up. Intake is on. Going to take the engine to the dyno later this week, and fire it up. I believe only one pre-fire question remains. For the MSD EFI distributor (23451) with Hall-Effect cam sync sensor, I have the wiring set. Does the distributor need any special install? Or simply follow the MSD instructions? (Which is what I would have guessed.)
    Last edited by Velocity540; 11-18-2014 at 07:18 PM.

  6. #26
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    Quote Originally Posted by Velocity540 View Post
    Does the distributor need any special install? Or simply follow the MSD instructions?
    See section "2.0 Cam Sync Positioning":
    http://forums.holley.com/showthread....m-Sensor-Setup (Crank & Cam Sensor Setup Instructions)
    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.

  7. #27

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    Fantastic. I will bookmark that page!

  8. #28

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    Quote Originally Posted by Danny Cabral View Post
    See section "2.0 Cam Sync Positioning":
    http://forums.holley.com/showthread....m-Sensor-Setup (Crank & Cam Sensor Setup Instructions)
    Example - 8 cylinder with a Ignition Reference Angle of 60°
    Cam Sync Location = 60 + 90 + 90/2 = 195 degrees BTDC #1
    Cam Sync Location = 60 + 90 + 45 = 195 degrees BTDC #1
    195° would be the centrally "perfect" location for this specific example.

    I will be setting my Ignition Reference Angle at 60°. Obviously BBC 8 cylinder.
    So, looks like the example works for me. Value comes out to 195°. Simple math.

    http://s1206.photobucket.com/user/dj...mSync.jpg.html
    Looking at the above picture, I will rotate the motor till it's at 195° BTDC #1 cylinder.
    Then, I'll set my cam sensor (on MSD distributor) to line up with the marker on the MSD distributor shaft? Correct?

    What cylinder would the rotor be at? I believe I would be one tower over from the #1 position?

  9. #29
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    Quote Originally Posted by Velocity540 View Post
    Looking at the above picture, I will rotate the motor till it's at 195° BTDC #1 cylinder.
    Then, I'll set my cam sensor (on MSD distributor) to line up with the marker on the MSD distributor shaft? Correct?
    Yes, that's the point of setting the cam sensor. Read that Link again.

    What cylinder would the rotor be at? I believe I would be one tower over from the #1 position?
    You're not aligning/phasing the rotor at this point; it doesn't matter where the rotor will be pointing.
    The distributor & rotor will already be initially positioned from setting the crank sensor/distributor.
    If this confuses you, simply install the EFI distributor as you normally would, then set the cam sensor afterwards.

    With a crank trigger, turning the distributor only adjusts rotor phasing.
    The crank sensor sliding bracket, now does the task that turning the distributor once did.
    I would also ensure the distributor's "rotor phasing" is correct. MSD has a good video on why it's important:
    http://www.youtube.com/watch?v=aWMlNwGW0tM (MSD Tech - Rotor Phasing Video)
    http://08961cd535df487cd1c1-bda68e18...m/84211_tb.pdf (MSD Rotor Phasing Document)
    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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