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Thread: RPM drop rapidly when coming to a stop and engine wants to stall or does stall, after 116 Update

  1. #71

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    Glad to hear that and what you say definitely makes sense :-)

    BTW, another question: You said that you reset all settings to default right? You just did it within the handheld settings or did you do this root-reset thing I read about somewhere. There was once posted a link to a how to, but the link works no longer anymore.

    What I wanted to know if you just know about this root-reset of the handheld where also all learned parameters, etc., will be deleted. If YES, can you provide a link please? Thanks.

  2. #72

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    To answer above question, no I have not heard of the reset all procedure, but I will look now.
    I have come up with a custom procedure for setting the two piece rotor.
    - Follow MSD instructions and get to the point that timing gun shows 15° advance when "lock timing at 15" is selected on hand held.
    - Mark #1 plug post on cap down onto dist base with a sharpie.
    - Remove cap and bring engine so harmonic balancer it at your idle timing setting (probably 10-12°).
    - Rotate engine again until your harmonic balancer is at total timing setting (probably 36°-38°, you need timing tape on the balancer for this).
    - Setup two piece rotor so the rotor is aligned as well as possible with sharpie mark when at idle and at total timing spots. Go back and forth between the idle and total positions until the two piece rotor setting is perfectly aligned with the same orientation at both positions.

    I have read that the rotor should be best aligned at total timing since cylinder pressure is highest at that point, but I am ignoring that, since the above procedure probably yields a very good setting and is relatively easy.
    I'll post again after doing above procedure on my 77 SBC 350.

  3. #73
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,506

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    I usually get an old cap and drill some holes an either side of the #1 post and then use a timing light to see where the rotor is at. And use thread locker on the screw that holds the top adjustable rotor. It has been known to come out.
    Last edited by 81 TransAm; 03-18-2020 at 10:12 AM.

  4. #74
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,114

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    Ensure you're using the correct Ignition Reference Angle for your distributor (inherent crank reference angle/rotor-phasing of the distributor). Rotor-phasing will be way off if it's wrong.
    http://www.masterenginetuner.com/top...all-fails.html (Crank Reference Angle Importance)
    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, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 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/3000 RPM converter, 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 MT tires.

  5. #75

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    Quote Originally Posted by 81 TransAm View Post
    I usually get an old cap and drill some holes an either side of the #1 post and then use a timing light to see where the rotor is at. And use thread locker on the screw that holds the top adjustable rotor. It has been known to come out.
    EXACTLY THAT happened to me last year one day on my way home. Thanks for the friendly reminder. Still need to get some thread locker :-)

  6. #76

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    Quote Originally Posted by Danny Cabral View Post
    Ensure you're using the correct Ignition Reference Angle for your distributor (inherent crank reference angle/rotor-phasing of the distributor). Rotor-phasing will be way off if it's wrong.
    http://www.masterenginetuner.com/top...all-fails.html (Crank Reference Angle Importance)
    Is crank reference angle adjustable on MSD Atomic? I see how that would throw off rotor phasing after reading the article. Maybe drilling holes in an old cap is the ultimate way to check. If I were to adjust to perfection, would the rotor be closer to the post at full advance or equidistant at full and idle advance states?

  7. #77
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,114

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    I don't have the Atomic EFI (so you tell me), but the Ignition Reference Angle is usually adjustable/programmable.

    Originally Posted by Danny Cabral
    Testing the MSD CD ignition box.
    Points Output - white wire & Magnetic Pickup - violet/green triggering:
    https://www.msdperformance.com/suppo...ng_techniques/ (Troubleshooting Info)

    Ensure the distributor's rotor-phasing is correct:
    http://documents.msdperformance.com/8644_tb.pdf (MSD Rotor-Phasing Document)
    MSD has a good video on why it's important:
    http://www.youtube.com/watch?v=aWMlNwGW0tM (MSD Tech Rotor-Phasing Video)

    For naturally aspirated engines, the rotor is usually phased halfway between minimum & maximum amount of timing advance used.
    For forced induction engines, the rotor is usually phased at maximum boost retard, because that's when cylinder pressure is the greatest.
    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, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 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/3000 RPM converter, 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 MT tires.

  8. #78

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    I spoke too soon. It's still doing the anoying almost stalling/sometimes stalling at stops! As a test I clocked the two piece rotor closer to 0°, adjusted vacuum advance (on the handheld) down a bit. No difference, it decides to intermitently almost die at stops either way. I'm guessing there's something else I have not addressed whatsoever causing the issue.
    Things I have tried:
    - Fuel pressure regulator (old one was leaking anyways).
    - Tried PWM and non-PWM mode.
    - Adjust two piece rotor.
    - Adjust base timing and timing settings on handheld.
    - Swap intake manifolds and cut down wall between dual-plane halves.
    - Verify no vacuum leaks (at least when I was checking).
    - Swap PCV to lower flow PVC from newer injected gm product.
    - Verify wiring, looks good, well connectedM
    - Did throttle plate base idle adjust once or twice.
    - Installed old fashion dash pot on throtlle linkage (removed after no improvement).
    - Checked for exhaust restriction.
    - Reset all settings.

    I'm wondering if there's a way to datalog and send it to MSD (like I'd be able to do with my Holley Sniper, except it works really well and I wouldn't actually need to do that).

  9. #79
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,506

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    Two causes of stalling when returning to idle are, improperly tuned Base Fuel Table and improperly set throttle shafts.

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