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Thread: 351W ignition cutting out at low RPM take off.

  1. #1

    Default 351W ignition cutting out at low RPM take off.

    Stock bottom end
    Ford E303 roller cam
    Trick Flow 170
    RPM Air-Gap intake
    Hedman shorty headers
    MSD Pro-Billet locked out with 6AL
    Stock C4 with 1800 stall

    Atomic EFI settings as follows:
    Cam Type=Mild
    Fuel Pump=PWM No Reg
    Idle RPM Target=800
    Rev Limit=6000
    Timing Controls=On
    A/F Targets:
    Idle=14.0
    Cruise=14.0
    WOT=12.8
    Nitrous=Off
    Boost=11

    Ignition Timing Settings
    Idle RPM=1000
    Total=2500
    Idle Advance=10°
    Total advance=34°
    Vac Advance=9.0°
    Vac Type= Ported
    Nitrous Retard=Off
    Boost Retard=0.0°

    Pump Squirt=25
    Power Valve Enrich=20
    No codes displayed.

    Engine locks out at 15° perfectly and goes through my targeted RPM range when unlocked, but seems to be scattered upon a slow acceleration then cleans up over the rest of acceleration. I’m thinking it’s a setting, but not sure where to start. Any suggestions?
    Last edited by vcecontractors; 05-08-2019 at 07:52 AM.

  2. #2
    Join Date
    Oct 2018
    Posts
    28

    Default

    Idle Advance 34°? Do you mean Total Advance 34°? Idle Advance is around 10°-15° and Total Advance around 34°. Regards.

  3. #3

    Default

    Sorry, I made the correction. It is 10° & 34° as you described. Any suggestions on what cause it to break up on slow take off like that?

  4. #4
    Join Date
    Oct 2018
    Posts
    28

    Default

    Hey. I had also an issue like you are facing right now, and in my case, the vacuum advance settings fixed the issue. The vacuum type should be set to ported (as it already is) and keep playing around with the vacuum advance. Or another possibility may be the idle RPM setting which you set to 1000. This defines the RPM where Atomic starts advancing the ignition timing off idle. So actually at 800 RPM the timing is 10°, but the ignition timing begins advance from 1000 due to your settings. So I would try either to increase the idle timing from 10 to 12 or to lower the idle RPM (the point where timing begins to advance) from 1000 to 900. Another possibility is as already stated, the vacuum advance setting. Where you can play around with the value. Keep in mind that the vacuum advance setting is only used/activated when Vac Type = Ported and you hit the pedal so that throttle position changes from closed to open. I think in your case it's just a matter of fine tuning.

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