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Thread: $EE LT1 PCM Questions

  1. #1
    Fuel Injected! Terminal_Crazy's Avatar
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    $EE LT1 PCM Questions

    Whilst comparing .bins I came across these two inb the XDF.
    126d5 Min Inj Pulse
    126d7 Use this value when Min Inj Pulse reached

    The stock Z28 was set at 1.4ms. A tune I had made years ago had the Min Inj Pulse lowered to 1.01ms but the Use value.
    On checking logs I had injPW going lower than 1ms whilst cruising so does this value get used or does the PCM just dump fuel in.


    Also I was trawling through some of the LT1/LT4 dissassembly files & it mentions Pump shot a couple of times.
    These
    2021 Timer to cut fuel for Corvette Special Diagn
    12021 Vs Delta tps for?? burst Knock or low baro calc threshold for 2413 v 2414 for % airflow Calc
    12413 mult for % airflow calc if delta tps > 2021 Z28 & LT4 set at 2.0
    12414 mult for % airflow calc if delta tps < 2021 Z28 0.75 - LT4 1.04
    1240a Mas air/Cyl Filter Coefficient Vs map Vs rpm

    were around the same area so I was wondering if these were mis labeled.
    Something I will have a play with when the new injectors arrive.


    Also I have the Rev limiters/ fuel cut off maxed out but also came across this one with a lower value.
    167b4 MAX RPM for 0 bpW - max allowed is 6375
    Is this an extra fuel kill for over reving?
    I wasn't able to test this one out as the roads are a bit cold & wet & the car kept going sideways.


    thanks
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  2. #2
    Fuel Injected!
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    So far I have checked the hardcoded RPM limiter at 167B3. The labels in EEXtra were not correct, there you go with good ones:

    0x167B4 Hardcoded Rev Fuel Cut
    0x167BA Hardcoded Rev Fuel Resume

    Conversion is X*31.25 for both.
    Stock files have this limiter set to 7187.5 RPM, both cut and resume. Max possible value is 7968.75 RPM.

    Attached corrected XDF.

    More as I have it.
    Attached Files Attached Files
    Last edited by dzidaV8; 01-01-2018 at 10:22 AM.

  3. #3
    Fuel Injected! Terminal_Crazy's Avatar
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    Nice one!
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  4. #4
    Fuel Injected! jthompson122183's Avatar
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    Quote Originally Posted by dzidaV8 View Post
    So far I have checked the hardcoded RPM limiter at 167B3. The labels in EEXtra were not correct, there you go with good ones:

    0x167B4 Hardcoded Rev Fuel Cut
    0x167BA Hardcoded Rev Fuel Resume

    Conversion is X*31.25 for both.
    Stock files have this limiter set to 7187.5 RPM, both cut and resume. Max possible value is 7968.75 RPM.

    Attached corrected XDF.

    More as I have it.

    Thanks for posting this information, I haven't labeled much on the e-side since ive started a couple of years ago with this eextra project.
    97z28 A4 obd1 swap(16188051)
    Tunerpro Newbie

  5. #5
    Fuel Injected! jthompson122183's Avatar
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    "Pump Shot"

    Capture.JPG
    97z28 A4 obd1 swap(16188051)
    Tunerpro Newbie

  6. #6
    Fuel Injected! jthompson122183's Avatar
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    1240a
    from lyndon wester of westers garage in the facebook group "Tunercat Users"
    Capture1.JPG
    97z28 A4 obd1 swap(16188051)
    Tunerpro Newbie

  7. #7
    Fuel Injected! Terminal_Crazy's Avatar
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    Can you send a higher res image of that, I can't read it,

    Thanks
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  8. #8
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    Quote Originally Posted by kur4o View Post
    So i took another look at the supposed pump shot adder. After I examined some logs of data, I finally figured out what is does.
    At rapid tps change, the maf readings jumps alot too fast, the pcm use this pump shot as a scale factor to gradually increase or decrease the AFGS.
    For example the AFGS jumps from 20 to 100 g/s at one frame interval. PCM blends the increase to 30, 50, 80, 100 over a period of couple of frames. That way you don`t get erratic jumps in fuel bpw and engine runs smoother and more consistent.

    So this factors how fast the transitions happen. I guess the lower the value the faster the transition. Still it needs to be confirmed.
    It turns out maf reacts faster than the time needed for the air to get to cylinder. That`s why there is no ae build in the code.

    That is the final explanation for the so called pump shot adder.
    It took me about a year to figure it out and some customs logs to confirm it.

  9. #9
    Fuel Injected!
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    Quote Originally Posted by Terminal_Crazy View Post
    Whilst comparing .bins I came across these two inb the XDF.
    126d5 Min Inj Pulse
    126d7 Use this value when Min Inj Pulse reached

    The stock Z28 was set at 1.4ms. A tune I had made years ago had the Min Inj Pulse lowered to 1.01ms but the Use value.
    On checking logs I had injPW going lower than 1ms whilst cruising so does this value get used or does the PCM just dump fuel in.


    Mitch
    The logged data don`t correspond to actual data the PCM uses.
    The BPW on the datastream is base data that is not corrected with individual fuel trims, Low pulse injector adder and min injector pw.
    So in your case when the minimum injector pulse is reached PCM load 126d7 for bpw even that you don`t see it on the datastream.

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