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Thread: Surge up & down at idle very hard starting. Was working great.

  1. #1

    Default Surge up & down at idle very hard starting. Was working great.

    Hi, I have a '66 Toronado with Atomic EFI and MSD 6AL with timing control. Has been running great for 600 miles. Had and issue with fuel pressure going down but cleaning the throttle body seemed to fix it completely. I have a return line so no vapor lock has NOT been noticed.

    Now suddenly I have hard starting and very bad idle. If I lock the timing at 15° the engine will start and run but idle is not stable. I was able to verify the timing was at 15° and the rotor is properly seated. Ignition wiring is all good. When I unlock the timing the engine may not start if it does there is a lot of back fire and surging up & down. I have verified there are not any failed wires or the like. There are no errors shown on the diagnostic screen. Is this an MSD 6AL ignition problem or an Atomic EFI problem? I have searched for vacuum leaks, but have not found anything.

    Here are some more details. Today I changed the WBO2 sensor to a new one just in case and no effect. Again this was running great until yesterday then now I get the aforementioned surging and hard starting. No vacuum leaks detectable. No wiring issues are obvious. I have noticed that the MSD 6AL digital light is constantly in the ON mode. According to the manual however, this is not supposed to be the case. It's supposed to do one long flash followed by 5 short flashes and then flash each time the ignition fires. So that is strange. The MSD 6AL also appears to be stuck in rev limiter mode now.

    When it does run the A/F Ratios are all over the place, which is why I replaced the WBO2 sensor but no change. Setting are as follows (running fantastically until yesterday) lots of power and no backfires.

    Idle Target 675
    Timing:
    Idle RPM 575
    Total RPM 1800
    Idle adv 12°
    Total adv. 15°
    Vac Type unported

    Idle 13.0 AFR
    Cruise 13.5 AFR
    WOT 12.5 AFR
    Last edited by toronadoproject; 09-22-2019 at 12:18 PM. Reason: more details added

  2. #2

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    Have you ever looked if the rotor bolts didn't come loose? Did you change the type of camshaft?

  3. #3
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
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    1,533

    Default

    How did you verify rotor phasing? What rotor are you using? Gary
    Regards, Gary

  4. #4

    Default

    I'+m using the MSD distributor and a lockout rotor from MSD. Yes, I checked those and all were good. I checked the rotor using a cap with a hole in it and watching the alignment with a timing light just like in the MSD video. It was phased perfectly. The rotor was rock solid and aligned perfectly. So I continued with my testing and I cleaned the throttle body a bit with the spray MAP cleaner. I don't know if the cause is the new WBO2 sensor or the cleaning, but the engine stopped the oscillation as I kept testing. Now it's operating stably. I can't figure out why this happened. I've since replaced the MSD 6AL since it was not acting as it should, but that did not really make any difference.

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