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Thread: 95 LT-1 Idle Cell Comparison - Humidity?

  1. #166
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    Is it dumping more fuel or it is starving.
    I'm thinking it was starving, but probably not due to a calibration fault. I noticed when I shut it off I could hear the pump running quite a bit longer than usual. It occurred to me this morning it was probably sucking air (the fuel gauge has been reading near E for a day or two). When I peeked in the filler cap I could plainly see the pump's filter sock, and it seems like the pump might have popped out of the bracket. The y-body fuel tank design is one thing GM solidly botched.

    After adding a few gallons and re-priming the system, cold start at 6.5c popped right off. So the O2 shift I mentioned on both sides may be invalid due to air in the fuel system.

    Quote Originally Posted by kur4o View Post
    The stock settings are
    My stock bin had this for the 12df2 table:

    Code:
    20
    20
    20
    20
    40
    40
    40
    60
    60
    60
    60
    60
    60
    60
    60
    60
    60
    Quote Originally Posted by kur4o View Post
    There is also baro correction applied

    ,,,

    The baro table runs from 53kp to 104.44kp and stock setting are -3 to 0* EOIT added to main EOIT table.
    On lt1 and y and f body the baro correction is set to 0.
    Very interesting find.

    Quote Originally Posted by kur4o View Post
    There is some alient math there, that substract fuel on certain condition, possible compensation for the fuel left on the walls unevaporated.
    This is referred to as Tau in the Banish stuff I have.

  2. #167
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    There is also baro correction applied

    ...

    The baro table runs from 53kp to 104.44kp and stock setting are -3 to 0* EOIT added to main EOIT table.
    I've been thinking about this - is this adder before the 5.625 multiplier? If not it seems somewhat pointless.

    Quote Originally Posted by (google)
    The boiling point is reached when the vapor pressure of a liquid matches the atmospheric pressure. Raising the atmospheric pressure will raise the boiling point. Conversely, lowering the atmospheric pressure will lower the boiling point of the liquid.
    This makes sense, except that at closed TPS evaporation will be taking place inside the port at well below atmospheric pressure. Makes me wonder if there's a closed throttle check happening before the adder.

    On the subject of EOIT ramp out mulitplier:

    Quote Originally Posted by kur4o View Post
    There is 1 way to test it. Monitor the eside word_a9 while changing the EOIT target from end to end on the controller window with ignition on.
    To do it open raw window in eehack, and loop in 50ms interval the command e4 ... 03 00 a9 00 aa , you will get a response with the word_a9.
    Will this work with engine running or must it be off? I initially overlooked the words "with ignition on", tried with engine running and got the below error.

    raw-command-dialog.png

    Thinking about it, I assume this can't be done with engine in operation because it's on the e side?

  3. #168
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    The boiling point lowers with lower atmospheric pressure. The only example I can think of is that you can`t boil eggs on a airplane`s high altitude since the water boils at much lower that 100*C temperature.
    In high vacuum situation the fuel will boil and evaporate at lower temperature. I think that is also taken into account in transient fuel calculations and maybe that is the point of it. The evaporation rate of the fuel is not constant and that`s why the transient fuel routine only substract fuel, but never adds it. If that is somehow related with the camshaft events the lt4 transient calibration might be set different.

    is this adder before the 5.625 multiplier?
    It is added to the calculated EOIT table value. This multiplier is not used by the pcm, it is only to convert the hexvalues to human readable degrees.

    I assume this can't be done with engine in operation because it's on the e side?
    Only with IGN on, engine OFF the eside talks on the bus. With engine on the pcm is too busy to handle aldl requests.

  4. #169
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    This multiplier is not used by the pcm, it is only to convert the hexvalues to human readable degrees.
    So the -3 would be a raw value, and would change eoit by ~17 degrees. That makes sense.

    Either way, with a base at 0x50 or 270 ATDC that seems like a fairly small amount of evaporation time for aluminum heads based on our sweep tests.

    It does give me another variable to go back and look at though - I didn't pay attention to baro when I generatd my sweep test data.

  5. #170
    Fuel Injected! spfautsch's Avatar
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    Seems like prime pulse tables are good - "good enough" at the very least considering no fine tuning has been done. Longest cranking time has been 1.0s and shortest 0.5. Using the spreadsheet (latest update attached) I found adding 2.5% on top of the displacement adder has been starting reliably from 7c up. Warm and hot restarts seem good, but it's hard to tell now because ambient hasn't been above 30c in nearly three weeks.

    Thanks for putting your work on the 121F1 table up. I had to move it out of the garage for a minute yesterday and did so while it was cold and it was noticeably smoother and stronger slipping the clutch while backing up the apron and into the garage with this change. In the absence of an "official" spark vs AFR compensation table this does the trick.

    Another tidbit I wanted to leave with - having complained about fuel smell... I had basically run it to empty last week and grabbed a can of the ethanol free fuel I bought a few months back and dumped a couple gallons in. It's been years since I've smelled real gas burning - while it still has a strong smell at first, once the engine has been running a few minutes, and especially in closed loop it's nowhere near as rough on the eyes. I'm anxious to get my wideband functional again so I can compare as I run the real dino gas out and then refill with more ethanol "contaminated" fuel.
    Attached Files Attached Files

  6. #171
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    After some down time I managed to merge the 2 versions of the source code. I added the checksum improvements you have suggested.

    Ported most of the function in a key shortcut. There is a side effect for the key cuts that I really like.
    Now you press I once and the 1-9 and 0 are now tied to idle trims. Press O and they are tied to off idle trims.
    So there is no need for I+1...0, even though it also works.

    Info buttons are empty for now. A write up needs to be done.

    Give it a try and check for any unusal stuff, it might needs some more polishing.

  7. #172

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