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  1. #1
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    Mike
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    Default Lean Tip In w/OBD1

    Wondering if anyone has a preferred method for combating lean tip in with the 051 OBD1 pcm with a MAF tune, specifically at sudden WOT? I seem to be getting a lean spike when quickly mashing the gas so the throttle response could be better. The car will occasionally stutter (maybe once every 25 times) if I roll into it fast enough. The AFR adjusts pretty quickly and it has no problem getting high 12's AFR until redline, but it takes several cells to get there on both the narrow and wideband.

    TPS voltage is normal, no vac leaks or other weird things. I also noticed a MAF spike a while back when it happened and thought the MAF was going out. It didn't seem to affect the inj pw that much though. Swapped to a different one with the same results. I also redid the MAF wiring with no change.

    Other details:
    -Burst knock is disabled. I'll probably re-enable it as a bandaid and see if the occasional stutter goes away.
    -Never had a problem with a stutter until swapping to a 58mm tb and ported intake. Probably allows me to get too much air too quickly. Guessing the lean spike was always there, now it's just more pronounced.
    -Transient fueling is enabled.
    -I think the PE thresholds are 20% tps and 80kpa? I'll have to double check.

    I read about a mysterious pump shot adder that dumps fuel based on sudden changes in throttle position. AFAIK it's not in EEX or EEXtra, so I'm unsure how I'd go about changing it without a definition.
    96Z M6, ERE-383 #60, AFR 210s, LE cam, 9", 414whp sae, awaiting boost
    95 Roadmaster T-56 swap, LE1s, cc304 w/1.7rr, 4.56s, "The Cammaster"

  2. #2
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    Karl Ellwein
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    Default

    Mike, have you figured this out yet? Any info you have would be good learning. How is the forced induction tuning coming along?

  3. #3
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    Default

    Quote Originally Posted by Karl Ellwein View Post
    Mike, have you figured this out yet? Any info you have would be good learning. How is the forced induction tuning coming along?
    I did some digging and found out that a pump shot adder does exist in the tune but I haven't had a chance to play with it yet. There's a 3x3 table called 1240a that has the MAF coefficients in them with MAP/RPM boundaries defined by scalars elsewhere in the tune (just like closed loop fueling cells 0-15 and their respective MAP/RPM boundaries). I saw values ranging from 0.09-0.12 but wasn't entirely sure what the numbers correlate to. Allegedly, a lower # corresponds to more enrichment but there's a lot of uncertainty around this.

    I compared the values between a LT1 and LT4 bin and noticed that the LT4 values were generally higher (ie less enrichment) which seems counter intuitive. I'm also unsure if it's a simple adder that dumps fuel based on %TPS or %airflow change or if it's some sort of dampening coefficient that allows MAF spikes to have more impact on fueling in the short term. I'm going to do some experimenting with it and see what happens because burst knock seems like a crappy bandaid.

    1240a and the other scalars aren't in the regular EEX definition. There was some goofy modified version of EEXtra posted on gearhead-efi that I found it in, I'll have to check my XDF's and see which one it was because I don't remember off the top of my head.

    I'm still running around NA at the moment but I have pretty much everything to put the D1 on. Once the weather gets cold and I figure the tip in issue out, I'm gonna throw it on as a low boost setup... this winter hopefully.
    96Z M6, ERE-383 #60, AFR 210s, LE cam, 9", 414whp sae, awaiting boost
    95 Roadmaster T-56 swap, LE1s, cc304 w/1.7rr, 4.56s, "The Cammaster"

  4. #4
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    Default

    Here's a link to the XDF I found it in. I tried uploading it here but the forum doesn't support .xdf attachments.

    http://www.gearhead-efi.com/Fuel-Inj...5&d=1508791730
    96Z M6, ERE-383 #60, AFR 210s, LE cam, 9", 414whp sae, awaiting boost
    95 Roadmaster T-56 swap, LE1s, cc304 w/1.7rr, 4.56s, "The Cammaster"

  5. #5
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    Karl Ellwein
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    Default

    Thanks for the link. I need to subscribe to that Gearhead efi form.

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