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Thread: 2-4 Stumble

  1. #1

    Default 2-4 Stumble

    Hello all. I have a Holley HP EFI with a Holley 4BBL TBI. On a smooth steady throttle the engine will pull like a rocket right through WOT. But if I stomp it quickly, it will stumble right when the secondaries open. My 4 BBL opens at 48% throttle, I currently have my 2-4 switch set at 45%. I'll try changing that to 58% tomorrow and see what happens. Pretty sure it goes lean at this point, but can not look at laptop while driving. Saw the post on updating my AE vs TPS RoC & AE vs MAP RoC, I'll need to change them. Running V3 software now. Any help would be appreciated. Thanks, Jim

  2. #2
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    Quote Originally Posted by ecmauto View Post
    Saw the post on updating my AE vs TPS RoC & AE vs MAP RoC, I'll need to change them. Running V3 software now. Any help would be appreciated. Thanks, Jim
    Which AE Correction vs TPS scale are you using?
    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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    LOL! OK, you got me. I'm not sure what you are asking. In my Fuel ICF, under the AE tab there are 6 tables, one of which is labeled AE Correction vs TPS. I only have one scale to choose. That scale runs 0-100% in TPS Position & 0-300% in AE Correction. Am I missing something?

  4. #4
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    Quote Originally Posted by ecmauto View Post
    ...one of which is labeled AE Correction vs TPS.
    Yes, that's the one. What's the scale cell values? The TBI injected applications with a progressive secondary throttle linkage, use a center spiked AE Correction vs TPS curve where the secondaries begin to open (and secondary injectors begin spraying). Is this the case with your AE Correction vs TPS scale? It should be, but you may have to adjust where the center spike occurs (according to TPS Position %).
    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

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    Hi Danny, the spike starts at 26% and maxes out at 40%, before it starts to fall. It never goes below 100%.

    I might have just found something. I noticed that in my System ICF under Closed Loop/Learn, Closed Loop Parameters I had "Enable TPS To Enter Open Loop" turned on and set to 50%. Which means since my 4 BBL opens at 48%, the Base Fuel Table was not being Learned in the area when it stumbles. Now since it seems to run pretty good on a smooth steady throttle in that area, my Base Fuel Table can't be to far off. Can it?

  6. #6
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    Quote Originally Posted by ecmauto View Post
    Hi Danny, the spike starts at 26% and maxes out at 40%, before it starts to fall. It never goes below 100%.
    If your secondaries begin opening at 48% TPS, you may want to try moving that AE Correction vs TPS spike a little further in TPS Position.

    I might have just found something. I noticed that in my System ICF under Closed Loop/Learn, Closed Loop Parameters I had "Enable TPS To Enter Open Loop" turned on and set to 50%. Which means since my 4 BBL opens at 48%, the Base Fuel Table was not being Learned in the area when it stumbles. Now since it seems to run pretty good on a smooth steady throttle in that area, my Base Fuel Table can't be to far off. Can it?
    Go through every screen of the EFI software and ensure everything is correct. This should've been done when creating your Global Folder.
    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. #7

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    Hi Danny. 1ST, YEE HAA! Thank you for the help! I corrected the RoC Blanking value's to correspond to my EFI software version, updated my AE Correction vs TPS spike to closer match my secondary opening, and turned my Enable TPS To Enter Open Loop off. What a difference. Smooth clean throttle with no stumble. Thank You!

  8. #8
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    You're welcome. I glad it's running good now.
    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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