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Thread: Dis'd my 3.4, how to set dwell in $88?

  1. #1
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    Dis'd my 3.4, how to set dwell in $88?

    Threw away the dizzy in favor of dis. I can find dwell adder settings in $88, but can't seem to find base dwell settings. Please help!

  2. #2
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    Dwell in code is dynamically calculated. I've never adjusted the calculations or limits for the DIS conversion. IIRC I compared a couple of cals once and found DIS was using same values as distributor which made me believe DIS module handles dwell.

    I do change spark latency settings.

  3. #3
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    What's spark latency?

  4. #4
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    Time delay between ecm saying "make spark" and spark actually appearing at the plug.

  5. #5
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    I found two items in $88 that could be related, but, like dwell, I couldn't find a latency item.
    Would "domain correction to spark" (KTIMELAG) be what I'm looking for? It's set at 381.47usec for a dizzy.
    I also found "Spark pulsewidth threshold" (KK42PLWD) which is set at 0.001sec.
    What kind of lag would I set for dis?
    Ron

  6. #6
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    KTIMELAG is the correct variable. Sorry, but I don't happen to know the numbers. I usually open up a DIS calibration to check. $A1 is for a DIS equipped 60 degree V6.

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    Ok. I've done A BUNCH of reading and found that A1 uses a latency value of 153 Usec. So I've got to change that.
    I've also read that the dis icm handles dwell, so the ecm is not involved, so does that mean I need to zero out any dwell adders in $88?

  8. #8
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    LEave the dwell numbers alone. Checking code/cal between early DIS and dizzy shows GM didn't alter dwell calcs.

  9. #9
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    Ok. Thanks!

  10. #10
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    Just an FYI where latency is concerned. I used a dizzy code on one of my cars, then converted to DIS. At first I left that setting alone. I changed it after a while when I remembered about it. After changing it I seemed to have what seemed like timing issues and the car got difficult to drive. Tried adjusting the SA table to compensate. But never recovered. So I went back to the original latency setting and left it that way. I'm still not sure why it would have caused the issue it did, but you may find that using the original setting works best.
    The man who says something is impossible, is usually interrupted by the man doing it.

  11. #11
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    Ok. I'll watch it closely and check it against a timing gun. You guys are AWESOME!

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