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Thread: Bad Vibrations

  1. #1
    Join Date
    May 2018
    Location
    Dublin, OH
    Posts
    49

    Default Bad Vibrations

    I have a 1991 Mustang with a 347 and the HP EFI system, and I'm having terrible vibrations. The engine seemed to have lost power on the highway yesterday, I tried to floor it and it felt like I was at 1/3 throttle. At idle and under load during low RPM, there is terrible vibrations. The CL Comp seems to be okay, although on my morning commute I would see it around zero % at cruising, but sometimes it would go to -25+% while under the same condition. If anyone has anyone ideas, or anything to check, please let me know. I checked the transmission fluid and did a visual check this morning, but nothing was out of the ordinary. Thanks.
    347 SBF N/A hand built, 1991 Fox Body Mustang, rebuilt AOD, HP EFI 3.5" LCD display, 7" Digital Dash & both I/O Adapters. Dublin Ohio, 18 years old, built not bought.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,709

    Default

    Quote Originally Posted by paddyrk View Post
    The CL Comp seems to be okay, although on my morning commute I would see it around zero % at cruising, but sometimes it would go to -25+% while under the same condition.
    Maybe a failed WBO2 sensor.

    Diagnose The Following:
    All sensor values correct on Data Monitor?
    Failed WBO2 sensor corrupted Learn Table (unusual %)?
    Exhaust leaks upstream of the WBO2 sensor?
    Sufficient length of exhaust piping beyond WBO2 sensor?
    Ignition misfire? (WBO2 sensor will read lean.)
    Battery/charging system functioning properly?
    Consistent fuel pressure? (Disconnect vacuum hose to measure static psi.)
    Inspect wire harness/connectors for damage.

    Troubleshooting & Testing:
    https://www.holley.com/document/tech...__statuses.pdf (Sensor Diagnostics & Statuses)
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual & Diagrams)
    http://forums.holley.com/showthread....ist-Holley-EFI (Troubleshooting Checklist - Holley EFI)
    https://forums.holley.com/showthread...7668#post87668 ("Test Relay" for troubleshooting/diagnosis.)
    https://www.youtube.com/watch?v=rmnxKLjM25g (Wideband O2 Sensor Test/Diagnosis - it works!)
    If testing the WBO2 sensor key-on/engine-off, the sensor heater will time out, so you'll need to work fast.
    If you need more time, the WBO2 sensor test can be performed with the engine running in Open Loop mode.

    If anyone has anyone ideas, or anything to check, please let me know.
    You'll have to record & review a datalog of this occurrence.

    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
    Join Date
    May 2018
    Location
    Dublin, OH
    Posts
    49

    Default

    Here are my datalogs. The first starting when I idled in park then went for a drive & parked. The second is me starting the car after I parked it after the drive. I pulled all the spark plugs as well beforehand, and found one that was somewhat loose in the head, and it was still wet and reeked of gas, but when I held a flame to it, it did not catch. Other than that plug, the rest looked like this. Anything helps, thanks.
    347 SBF N/A hand built, 1991 Fox Body Mustang, rebuilt AOD, HP EFI 3.5" LCD display, 7" Digital Dash & both I/O Adapters. Dublin Ohio, 18 years old, built not bought.

  4. #4
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,388

    Default

    Always post your Global File with your datalogs.

  5. #5
    Join Date
    May 2018
    Location
    Dublin, OH
    Posts
    49

    Default

    This is my Global File.
    347 SBF N/A hand built, 1991 Fox Body Mustang, rebuilt AOD, HP EFI 3.5" LCD display, 7" Digital Dash & both I/O Adapters. Dublin Ohio, 18 years old, built not bought.

  6. #6
    Join Date
    May 2018
    Location
    Dublin, OH
    Posts
    49

    Default

    After replacing the coil, plugs, cap & rotor, the engine started much easier and ran better, but it still misses pretty bad. I used my timing light to make sure all the cylinders were getting spark, and sure enough, cylinders #2 & #3 were not receiving any. I did a visual inspection, changed spark plug wires, even went back to the previous cap, and nothing gave them any spark. All the other cylinders get plenty of spark. What could cause spark to only 6 of the 8 cylinders? Is there a way to datalog individual cylinder spark?

  7. #7

    Default

    If you have a multimeter, Ohm out the plug wires. If not, try swapping the bad wires to different cylinders.
    '95 Lightning, HP EFI, 351W, S472SX-E, 20 PSI,N2O,pump & W/M

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