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Thread: HP EFI slow to fire?

  1. #1

    Default HP EFI slow to fire?

    Have any of you guys used the HP EFI with a Holley dual sync distributor? Have you had any delays to fire at startup, when used with an MSD ignition box?

  2. #2
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    I haven't heard of this. And the Holley Dual Sync Distributor has become a popular choice (which requires a CDI box for single coil applications).
    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/3000 RPM converter, 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 MT tires.

  3. #3
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    If you are running sequential MPFI, the engine has to turn over a couple times, for the ECU to sense the position of the cam before it fires the injectors. I have noticed with mine, that it fires quicker with V4 than it did with V3. And I also spent some time to get the Cranking Fuel correct. This also helped it to fire faster.
    Last edited by 81 TransAm; 07-27-2016 at 04:49 PM.

  4. #4
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    Quote Originally Posted by 81 TransAm View Post
    And I also spent some time to get the Cranking Fuel correct. This also helped it to fire faster.
    You got that right. I spent months tuning my Coolant Temperature Enrichment & Startup Enrichment tables.

    Under 400 RPM, the ECU only uses the Cranking Timing, Cranking Fuel (lb/hr) & IAC Parked Position % tables.
    Sequentially injected engines will always crank slightly longer for the ECU to receive the cam sync signal.
    However, I wouldn't accept this as an excuse for not having fine tuned Startup Enrichment parameters.
    http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially Posts #2, #4 & #6)
    http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)
    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/3000 RPM converter, 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 MT tires.

  5. #5

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    The Gen 3 LS engines with the 24 tooth reluctor wheel, start scary fast with the OEM electronics. I saw reading a while ago that the ECU knows the position of the crank & cam within 1/4 revolution. My Gen IV engine with the 58 tooth reluctor, using a GMPP harness, doesn't fire nearly as fast as my previous LS6. Getting the Cranking Timing, Cranking Fuel (lb/hr) & IAC Parked Position % tables right, will make it fire faster. And as Danny said, this can take a lot of time. Andrew
    Last edited by andrewb70; 08-03-2016 at 08:22 AM.

  6. #6

    Default

    Thanks for the replies guys. The reason for asking is, I have HP EFI run in sequential mode with MSD 6AL & FAST dual sync distributor, and have previously posted with slow to fire issues (about 3-3.5 secs). Went through all the troubleshooting with forum guidance, and came to the conclusion it was a sync timing issue within the ECU, as it was not turning on the Points Output used to fire the MSD 6AL during the sync period. As soon as the ECU turned on the Points Output, the car fired straight away. I'm only running V3 software, so may see some improvement updating to V4. Obviously, the Holley dual sync distributor suffers the same issues when used in sequential mode, so no advantage changing distributors. Thanks again.

  7. #7
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    Install a distributorless ignition system, you'll never use a distributor, ignition module, CD ignition box or single coil again. Multiple coil ignition systems (CNP/COP/DIS) don't use CD ignition boxes.
    http://forums.holley.com/showthread....3038#post33038 (Detailed Crank Trigger/DIS Conversion Information & Reasoning)
    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/3000 RPM converter, 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 MT tires.

  8. #8

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    I understood that the Cranking Fuel & IAC Parked is acting like the AFR during cranking. What is the ideal AFR during that phase?
    I'm realizing mine starts easily without throttle when my engine is dead cold (Cranking Fuel 32 lb/hr @ 80°F) & IAC Parked @ 74%.

    Then if I leave the engine running for few minutes, switch it off & try to re-start it, long cranking then to fire it up. I need to almost crack the throttle 50%, so too rich I'd say. So I'd say either I should increase the IAC Parked or decrease the Cranking Fuel. And I don't have this issue when engine hot, so in between, it should be chaotic. What do you think?

  9. #9
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    Quote Originally Posted by Sponge View Post
    I understood that the Cranking Fuel & IAC Parked is acting like the AFR during cranking. What is the ideal AFR during that phase?
    No one can tell you what your engine's cranking air/fuel ratio should be at any particular temperature.
    This is user programmable EFI, you have to experiment with the Cranking Fuel (lb/hr) & IAC Parked Position % tables (& Fuel
    Prime Percent too). This is why I spent months fine tuning my Coolant Temperature Enrichment & Startup Enrichment tables.

    508 (8.3L) big block Ford:
    My Cranking Timing is 15°. My Fuel Prime Percent is 200% (MPFI). My Target A/F Ratio table is 14.2 in the idle area.
    My Cranking Fuel lb/hr: (below 0°F) 60, 55, 50, 45, 40, 35, 30, 25, 20, 16, 12, 10, 9, 9, 9, 9 (above 180°F)
    My IAC Parked Position %: (below 0°F) 100, 96, 92, 88, 83, 79, 75, 71, 67, 63, 58, 54, 50, 50, 50, 50 (above 180°F)
    My Coolant Temperature axis: -5, 10, 25, 40, 55, 70, 85, 100, 115, 130, 145, 160, 175, 190, 205, 220°F (180° thermostat)
    My Coolant Temp Enrichment %: 130, 127, 124, 121, 118, 114, 110, 107, 104, 102, 101, 101, 100, 100, 100, 100 (%)
    My A/F Ratio Offset values: -0.6, -0.5, -0.4, -0.3, -0.2, -0.1, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 (enriched AFR)

    302 (5.0L) small block Ford:
    My Cranking Timing is 15°. My Fuel Prime Percent is 200% (MPFI). My Target A/F Ratio table is 14.2 in the idle area.
    My Cranking Fuel lb/hr: (below 0°F) 40, 37, 34, 31, 28, 25, 22, 19, 16, 13, 10, 7, 6, 6, 6, 6 (above 180°F)
    My IAC Parked Position %: (below 0°F) 75, 68, 61, 55, 49, 44, 39, 34, 31, 29, 27, 26, 25, 25, 25, 25 (above 180°F)
    My Coolant Temperature axis: -5, 10, 25, 40, 55, 70, 85, 100, 115, 130, 145, 160, 175, 190, 205, 220°F (180° thermostat)
    My Coolant Temp Enrichment %: 130, 127, 124, 121, 118, 114, 110, 107, 104, 102, 101, 101, 100, 100, 100, 100 (%)
    My A/F Ratio Offset values: -0.6, -0.5, -0.4, -0.3, -0.2, -0.1, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 (enriched AFR)

    Under 400 RPM, the ECU only uses the Cranking Timing, Cranking Fuel (lb/hr) & IAC Parked Position % tables.
    Sequentially injected engines will always crank slightly longer for the ECU to receive the cam sync signal.
    However, I wouldn't accept this as an excuse for not having fine tuned Startup Enrichment parameters.
    If you take the time to study this, you'll be a startup tuning expert:
    http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially posts #2, #4 & #6.)
    Pay special attention to the "TIP" in post #6 of that same thread:
    http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially posts #2, #4 & #6.)
    Also, ensure all six of these points are properly adjusted and/or programmed:
    http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read Steps #1-#6!)

    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/techlibrary_199r10544.pdf (Holley EFI Help/Instructions Overview)
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual & Diagrams)
    Open the Holley EFI software "Help" Contents ("Help" drop down menu), and read "Step-By-Step Beginners Tuning".
    In Step-By-Step Beginner's Tuning, see the "Idle Fuel vs. Temperature" graphical representation - Figure 8, Section 5.1.
    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/3000 RPM converter, 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 MT tires.

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