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Thread: Amc 360 timing curve

  1. #11

    Default Amc 360 timing curve

    A very important note here.

    DO NOT USE THE THROTTLE BLADES TO ADJUST IDLE.

    This is not a carb and that is not a idle adjustment!

    The IAC will seek to adjust your idle. When it is not adjusted properly, your idle may be OK, but your performance will suck.

    The IAC target is not Zero. It can be OK at zero but target should be closer to 10-15 in park or 5-10 in Drive with your foot on the brake.

    Don't gloss over this process. It is very difficult but worth every hour spent. I have reset my blades at least 4 times now and every time I go over it, the performance gets better.

    Important adjustments:

    Always adjust both front and back exactly the same amount.
    The Front should move just slightly ahead of the rear (front opens first)

    There should not be a sucking sound when you start up or when you blip the throttle if it is adjusted correctly.
    Changing timing settings more than a couple of degrees can effect IAC

    Oh and based on some of your previous responses, It does not matter what the IAC reading is when you press the pedal down. It isn't doing anything accept at idle.

    Get this done right and you will be thrilled.

  2. #12

    Default Amc 360 timing curve

    + 1 on Fcsallan response. The IAC adjustment is an important step here.

  3. #13

    Default Amc 360 timing curve

    It is normal for the system to retard the timing if the actual idle speed exceeds the Target Idle Speed AND the IAC count is zero (IAC fully closed).



    As fcsallen and bojo have mentioned - the key is to get the throttle blades adjusted such that any fine tuning (idle speed trim) can be handled mostly by the IAC motor - with perhaps a little help from ignition timing (mostly for changes that occur more quickly than the IAC motor can react).



    If the IAC Count shows zero and your actual idle speed is still above the Commanded Idle Speed - then you need to continue closing the throttle blades a little at a time - until the IAC Count starts to climb.



    Your Idle RPM Target is 650 - yet you still have the blades adjusted so the engine is idling at 850 RPM and the IAC Count is zero. That is an indicator that you need to keep closing the blades until you see the IAC Counts start to climb - ideally stabilizing in the 10-15 range. If you miss it (go too far in either direction), it is best to start over. As the others have said - this can be a very tedious process until you get comfortable with it.



    However, the system will never operate as designed until this process is completed successfully.



    It is also worth checking to make sure your throttle cable / linkage is not hanging and preventing the throttle blades from closing completely each and every time. This scenario can have you chasing your tail for days.

  4. #14
    primosauce Guest

    Default Amc 360 timing curve

    I think I've been doing the wrong thing then. I'll set it back again, and adjust the screws in farther (CW) until the IAC count shows something. I've been adjusting it out to lower the idle even though it showed zero on the IAC. I'm assuming the throttle will fix itself then as the system learns?

  5. #15
    primosauce Guest

    Default Amc 360 timing curve

    ok, so I reset the screws at 3/4 of a turn cw from the zero movement point of the blades.



    It seems like it runs pretty well, more power thru the rpm range but it still idles at 1200 rpm give or take 70 rpm as it bounces around. Minor popping in the exhaust, it's pretty minimal, no major backfires or anything.



    I also noticed that when I shut the motor down there's poof that comes out of the exhaust, almost like unspent fuel in the pipe. It's not loud, just noticeable that somethings happening.



    IAC shows zero, but when you press the throttle it goes from 0 to 40ish depending on how hard you press the throttle and how aggressively you press it. Always 0 at idle.



    Now what should I do? I haven't turned the screws and I also drove it for about ten minutes just see if it would drop a little.



    It's definitely getting close, I feel like there is a light at the end of the tunnel here. I really appreciate your guys help. I was really close to switching this back to regular mechanical timing.

  6. #16
    primosauce Guest

    Default Amc 360 timing curve

    idle set at 750

    rpm target set at 850


  7. #17

    Default Amc 360 timing curve

    Do you have a manual or auto tranny? So were you able to get the IAC cnt in th 10-15 range? 3/4 turn seems excessive to me.



    Also can you list all your currents settings are now so we have a baseline to go from?



    Edit: I just saw you have a manual tranny

  8. #18
    primosauce Guest

    Default Amc 360 timing curve

    Currently it's at

    Target RPM: 750



    A/F is defaults



    Idle: 14

    Cruise: 14

    WOT: 12.8

    Nitrous: off

    Boost: 11.9



    Pump Squirt 25%

    Power Valve 19%



    Ignition Timing:

    Idle:850

    Total RPM:2500

    Idle Advance:8

    Total: 34

    Vacuum Advance:0.0

    Vac Type: Ported

    Nitrous: Off

    Boost Retard: 1.0



  9. #19
    primosauce Guest

    Default Amc 360 timing curve

    Really everything is default accept the timing settings and the vac advance is zero. I also have the rev limiter at 5500

  10. #20

    Default Amc 360 timing curve

    So did you ever get the IAC cnt to 10 to 15 while in neutral. It looks like you have the blades open too much right now from a couple of posts ago (IAC = 0). Also what is your timing doing at idle currently?

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