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Thread: A few Holley HP tuning questions.

  1. #1

    Default A few Holley HP tuning questions.

    Hi all. I have my 421 SBC running now using the Holley HP ECU and Terminator Stealth. A few questions.

    1) When I start it up cold, it starts fine, but then dies if I don't give it a little gas. What parameter might help with that? Fuel Prime Percentage? I have it at 150% I think.

    2) Also, sometimes if I rev the engine (in neutral), it'll want to die when it settles back down. Is that an IAC issue?

    3) Last, if I mash the pedal it takes a split second for the engine to catch up and then it revs quickly. Is that an acceleration enrichment setting that I need to increase?
    Thanks for any help you can provide.

  2. #2
    Join Date
    Dec 2009
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    Quote Originally Posted by hutchenc View Post
    1) When I start it up cold, it starts fine, but then dies if I don't give it a little gas. What parameter might help with that?
    See Coolant Temperature Enrichment % table & A/F Ratio Offset table tuning: http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially posts #2, #4 & #6.)

    If you take the time to study this, you'll be a startup tuning expert, and read the "TIP" in post #6:
    http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially posts #2, #4 & #6.)

    Fuel Prime Percentage? I have it at 150% I think.
    No, that's for the initial cranking to start.

    2) Also, sometimes if I rev the engine (in neutral), it'll want to die when it settles back down. Is that an IAC issue?
    Typical IAC Control/Ramp Down Parameter Settings
    Advanced Idle Control: ......................... Slow (Usually the best control.) Sniper EFI users select "Sniper TBI".
    IAC Type: .......................................... Stepper (4-wire), PWM (2-wire)
    IAC Hold Position: ................................ 10%-30% (Usually 15%-20%.)
    Ramp Decay Time: ............................... 1.0-3.0 sec (Usually 2.0 sec.)
    RPM Above Idle To Start Ramp: .............. 1000 RPM (Or higher.)
    RPM Above Idle To Re-enable Idle Control: 50-200 RPM (This setting can be finicky.)
    Startup IAC Position - Hold & Decay Time: 1.0-1.5 seconds (Less is typically better than more.)
    Not IAC, but Idle Spark control usually works well at: 30-40 P Term & 50-60 D Term.
    http://forums.holley.com/showthread....neral-IAC-Info (General IAC Information - Read "IAC NOTES")

    3) Last, if I mash the pedal it takes a split second for the engine to catch up and then it revs quickly. Is that an acceleration enrichment setting that I need to increase?
    Yes, see posts 2# & #8: http://forums.holley.com/showthread....9444#post29444 (EFI Acceleration Enrichment In Carburetion Terms)

    You should probably record & review a short datalog of this occurrence too.
    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

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    Thanks Danny, you're such a huge help. I'll see if I can resolve a few issues after I read through these posts.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,910

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    You're welcome, and thanks for the compliment.
    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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