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Thread: Random buck, help, supposed to road trip.

  1. #1

    Default Random buck, help, supposed to road trip.

    Driving the car today, it did something it's never done after a few thousand miles. The car bucked really hard a single time then just kept going like nothing happened. Did this three times on a short four mile drive. I started a datalog and was able to catch one before I got home. Here's the datalog, it happens at the 12.50 second mark. Fuel pressure is fine, injector pulse width is fine, MAP kPa good, & battery good. Any ideas? Only things I can see is that my RPM gets a little wonky, and the AFR goes stupid lean for a split second. Supposed to take this car on a 500 mile road trip this weekend...argh. Enclosed is the datalog. Any help greatly appreciated. Enclosed is a short clip of the datalog.
    Attached Files Attached Files
    Matt H. 1990 Mustang GT
    Dart 363, TFS 11R 205cc, Vortech Si-Trim, T56 Trans
    Cam: 227°/239° @ .050, .587"/.587", 114.5°+5 LSA
    Holley Terminator X EFI 550-937F

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    28,473

    Default

    Overlay the datalog onto your Config File, and 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 Config 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. When the engine is tuned & running well, you should decrease the Closed Loop & Learned Compensation Limits % to lock in a good tune.

    Using the Holley Terminator X 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 Config 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 Config File screen.
    Then click & scroll anywhere on the datalog, and watch it playback on your Config File (EFI software).
    http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions)
    https://forums.holley.com/showthread...s-amp-Datalogs (Datalog Information - Read "NOTES")
    https://www.youtube.com/watch?v=iqHO...C6FEA0BB99AF17 (How To Record & Email A Datalog)
    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 T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, R134a 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, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, 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 M/T Street Comp tires.

  3. #3

    Default

    I can see the cells that it's happening on, but it's never done anything like this before after thousands of miles of driving. Here's the tune, hopefully I attached it correctly. 363Dart2021oncar.zip

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
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    Look at the Base Fuel Table and the Learn Table, since they both function as one.
    http://forums.holley.com/showthread....1842#post61842 (Learn Table - Diagnostic/Troubleshooting Tool)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, R134a 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, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, 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 M/T Street Comp tires.

  5. #5

    Default

    Quote Originally Posted by vortech347 View Post
    Only things I can see is that my RPM gets a little wonky, and the AFR goes stupid lean for a split second.
    This, to me, screams ignition problem. I'd visually inspect all parts of the ignition system. Cap, rotor, plug wires & plugs. Andrew

  6. #6

    Default

    I'm having a similar issue. When cruising I get a random hard buck. My Base Fuel Table is smooth and the datalogs show a hard lean condition for a second. I'm thinking it's an ignition issue as well. I'm using the Ford TFI, I'm wondering if that's the cause.

  7. #7
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    28,473

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    If it's not ignition, see post #2 above. If it is ignition, wiggle test the Ford TFI module connector.
    https://forums.holley.com/showthread...280#post228280 (Related Forum Post - Ford TFI Connector/Terminals Issue)
    https://forums.holley.com/showthread...750#post225750 (Related Forum Post - Ford Motorcraft TFI Module/Distributor)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, R134a 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, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, 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 M/T Street Comp tires.

  8. #8

    Default

    Alright, so good news. I found it. I went on the 550 mile road trip, and had a blast! I narrowed it down to 1 of 2 possible issues:
    1) The connector for where the Dual Sync distributor plugs into the main harness had one wire on the main harness side that the pin had pushed backwards a little bit from the connector. I noticed the wire push out when I reconnected the plug. I just used some small needle nose pliers to hold it in place as I pushed the connector in. Since then I have a new female connector and pin set coming to redo it.
    2) The negative battery terminal clamp is a few years old now and after using it on & off the soft metal has broken down to the point where even though the bolt is bottomed out there was a little bit of wiggle. The car still started fine (usually if it's loose, a car won't start).

    So there ya go. Can't say specifically which one fixed it. I didn't notice if the connector pin was out of place to begin with, only after I went to plug it back in. I'm leaning towards the pin being the issue because the Holley never showed even the slightest bit of voltage issue in the datalog.

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