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Thread: Surging at Idle and light acceleration issue.

  1. #11

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    Quote Originally Posted by Proflyer View Post
    The surge may not change the RPM enough to show up in the datalog, but it does seem to correlate with the AFR spikes you see. It might misfire, WBO2 sees super rich, tries to compensate by going lean, then sees it's too lean and creates that never ending loop. I'll report back. Thanks gents!
    The wideband sees a misfire as a lean event, not rich. The more oxygen the wideband senses, the leaner it thinks the mixture is. Turn a wideband on sometime in free air and you'll see what I mean.

  2. #12
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    Quote Originally Posted by Proflyer View Post
    The surge may not change the RPM enough to show up in the datalog, but it does seem to correlate with the AFR spikes you see. It might misfire, WBO2 sees super rich, tries to compensate by going lean, then sees it's too lean and creates that never ending loop. I'll report back. Thanks gents!
    Quote Originally Posted by andyf View Post
    The wideband sees a misfire as a lean event, not rich. The more oxygen the wideband senses, the leaner it thinks the mixture is. Turn a wideband on sometime in free air and you'll see what I mean.
    I missed this earlier. Yes, a misfire is seen as a lean condition, high oxygen, and if that cylinder continues to misfire, the fueling goes rich for the rest of that bank. Only up to a point of maximum around 25%, otherwise the other cylinders drown. Gary
    Regards, Gary

  3. #13

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    That makes sense as to why the AFR spikes in the datalog. Replaced the plug boot and re-positioned it. I have about 1" of clearance between the boot and the header pipes on each cylinder. Shop here didn't think I needed those boots, as long as I don't mess with my plug wires and not notice one is resting on the head pipe. Oops.

    Car is running much better now. Turned my Learn parameter down to 1 from 3, as I have quite a bit of time on the Learn file now, and it seems to have cleaned up the idle, etc. a bit. Changing the AE vs TPS RoC really helped wake it up too. I had a bad stumble when I punched it, that's now gone.

    For more advanced tuning, should I take a longer datalog and upload that with my Config File for someone to look at? Thanks guys!

  4. #14

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    Car is running much better now. Turned my Learn parameter down to 1 from 3, as I have quite a bit of time on the Learn file now, and it seems to have cleaned up the idle, etc. a bit. Changing the AE vs TPS RoC really helped wake it up too. I had a bad stumble when I punched it, that's now gone.

    Please explain more about what you did to the RoC. What were the values before & after your changes. Thanks.

  5. #15

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    In the Sniper EFI software under fuel and AE Enrichment you’ll see a button for AE vs TPS. It’s a linear line that goes from high to low and at a certain point goes negative. I found someone talking about leveling off that change to where it flatlines instead of going negative. So I moved each point up to 100 (flat) that was negative. So instead of a constant linear downward line it goes down to 100, and then stays flat at 100. I’m not sure exactly what that changes, but when I punch it hard it doesn’t stumble like before.

    Holley help Contents says AE vs TPS is basically like the accelerator pump on a carb. Shoots a little extra fuel when you punch it. I’m sure someone else can add more color.

  6. #16

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    I believe you mean the "AE Correction vs TPS". To get to this you select fuel, then Acceleration Enrichment. Above the enrichment graph are six buttons. The one on the top right is called "AE Correction vs TPS". Any value below 100 actually reduces the "pump shot", so by flattening it out at 100 you stopped the ECU from reducing the pump shot, which is basically adding fuel to the pump shot.

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