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Thread: Bad hesitation from a stop.

  1. #1

    Default Bad hesitation from a stop.

    Hey guys. I'm trying to figure out why this car is getting such a bad hesitation right when you press the gas from a dead stop in gear. Idling in park and just revving it's seem fine. Driving the car around at lower RPM and giving it some gas, it runs fine. On the datalog, the problem is right at the beginning. As soon as the TPS moves, the fuel lb/hr spikes and falls rapidly. Is that normal? I've adjusted the TPS Acceleration Enrichment pretty steep to keep it from dying.
    Attached Files Attached Files

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,105

    Default

    Acceleration Enrichment can't be tuned until the Base Fuel Table is well tuned.
    https://forums.holley.com/showthread...589#post221589 (Related Forum Thread)

    Pay special attention to the center paragraph in blue print:
    Originally Posted by Danny Cabral
    Quick Datalogger Information:
    Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Global File.
    Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK).
    Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize:
    RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery.

    Using the Holley EFI software (LINK), look at where the live cursor moves to during this occurrence, and
    manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing).


    I find the most helpful datalog function, is overlaying the datalog on your Global File.
    I'm in the habit of using the datalog Overlay feature every time I review a datalog.
    Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log".
    You can literally "playback" a recorded event, and watch it as it happened on any screen.
    Minimize (shrink) the datalog window, and move it to the bottom of any Global File screen.
    Then click & scroll anywhere on the datalog, and watch it playback on your Global File (EFI software).
    http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions)
    https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES")
    https://www.youtube.com/watch?v=iqHO...C6FEA0BB99AF17 (How To Record & Email A Datalog)
    https://www.youtube.com/watch?v=q7OZUXLRS1Q (How To Record A System Log & Diagnose A No-Start Condition)
    https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts #2, #4 & #6)
    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

    Default

    What's the deal with the Fuel Flow spiking & falling? What causes this to happen? If I know why this is happening and get it to calm down, I think it would stop the hesitation.

  4. #4
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,454

    Default

    Always post your Config File with any datalogs you post. We also need to see your settings. The Fuel Flow spikes because of your MAP & TPS RoC. My guess, you're trying to cover up a poorly tuned fuel table with your MAP & TPS RoC. This is not the correct way to do things. You need to address the underlying problem, the Base Fuel Table.

  5. #5

    Default

    Kinda figured I was band-aiding something when I started adding so much Acceleration Enrichment to keep it running. I thought I had added more fuel than I did on the Base Fuel Table, but being in VE%, I really didn't end up adding all that much. I'll turn the Acceleration Enrichment back down and TPS RoC down and see if I can get it closer with just the Base Fuel Table. Thanks for the help.

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,105

    Default

    Yes, refer back to post #2.
    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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