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Thread: 95 lt1 injector offset questions

  1. #31
    Fuel Injected! Terminal_Crazy's Avatar
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    HI


    Do you mean another PCM?
    Yes, I don't have a spare atm.

    The only other thread I've read about surging not going away, the poster changed their cam.

    Have you double checked all your PCM grounds?
    Not yet but after cleaning/reseating the injectors I'll check all grounds & PCM connections as well.

    all the tables were expanded to use MAP. I'm interested in how you interpolated the data for the $EE tables.
    The Online Data doesn't mach up with the supplied data[/QUOTE]

    I originally emailed FIClinic:
    Which kPa value i would use for an LT1 with the 16188051
    OBD1 PCM for the Voltage offsets.
    The fuel system is the std 3 bar with the referenced FPR. So I'm thinking I
    would use 300kPa vaules from the table

    Response was: 300kpa values should work fine.


    Data supplied: I'll scan data sheet if anyone is interested.
    Slope flow matching data: Average flow rate at 43.5psi = 428cc/min. Your set is Flow matched within 1.9%
    Injector offset matching data: Average offset at 3bar & 13.5V 962uS. You set is matched within 1.4%



    In my notes Fuel pressure at Idle with Vac hose off is 47psi (which is what the engine should see under WOT)

    **** So we need to use the 47psi injector kPa value ===
    1 psi = 6.89476 kPa
    47 psi = 324.05372 kPa

    LS table Spacing is spaced 16.0kPa which is approx 2.3206038037 psi

    I don't use MS Excell but I do use Libre Office Calc and none that I have are able to Interpolate data...
    So I wrote a program to do a linear interpolation (don't ask about slope matching) to generate some nos.

    This gives Interpolated results of
    Volts Kpa From Next table
    0.000000 324.050000
    ========================
    0.400000 291.645000
    0.800000 259.240000
    1.200000 226.835000
    1.600000 194.430000
    2.000000 162.025000
    2.400000 129.620000
    2.800000 97.215000
    3.200000 64.810000
    3.600000 32.405000
    4.000000 0.000000
    4.100000 0.000000
    4.200000 0.000000
    4.300000 0.000000
    4.400000 0.000000
    4.500000 0.000000
    4.600000 0.000000
    4.700000 0.000000
    4.800000 0.000000
    4.900000 0.000000
    5.000000 0.000000
    5.100000 0.164857
    5.200000 0.329714
    5.300000 0.494571
    5.400000 0.659428
    5.500000 0.824285
    5.600000 0.989142
    5.700000 1.153999
    5.800000 1.318856
    5.900000 1.483713
    6.000000 1.648570
    6.100000 1.643023
    6.200000 1.637475
    6.300000 1.631928
    6.400000 1.626380
    6.500000 1.620833
    6.600000 1.615285
    6.700000 1.609738
    6.800000 1.604190
    6.900000 1.598643
    7.000000 1.593095
    7.100000 1.584205
    7.200000 1.575315
    7.300000 1.566424
    7.400000 1.557534
    7.500000 1.548644
    7.600000 1.539754
    7.700000 1.530863
    7.800000 1.521973
    7.900000 1.513083
    8.000000 1.504192 2.100000
    8.100000 1.492807
    8.200000 1.481421
    8.300000 1.470035
    8.400000 1.458649 1.967172
    8.500000 1.447263
    8.600000 1.435877
    8.700000 1.424491
    8.800000 1.413106 1.834345
    8.900000 1.401720
    9.000000 1.390334
    9.100000 1.377277
    9.200000 1.364220 1.701517
    9.300000 1.351163
    9.400000 1.338107
    9.500000 1.325050
    9.600000 1.311993 1.568690
    9.700000 1.298936
    9.800000 1.285880
    9.900000 1.272823
    10.000000 1.259766 1.435862
    10.100000 1.245878
    10.200000 1.231990
    10.300000 1.218102
    10.400000 1.204214 1.363448
    10.500000 1.190326
    10.600000 1.176438
    10.700000 1.162550
    10.800000 1.148662 1.291034
    10.900000 1.134774
    11.000000 1.120887
    11.100000 1.106987
    11.200000 1.093088 1.218621
    11.300000 1.079189
    11.400000 1.065289
    11.500000 1.051390
    11.600000 1.037490 1.146207
    11.700000 1.023591
    11.800000 1.009692
    11.900000 0.995792
    12.000000 0.981893 1.073793
    12.100000 0.968827
    12.200000 0.955761
    12.300000 0.942695
    12.400000 0.929629 1.024345
    12.500000 0.916563
    12.600000 0.903497
    12.700000 0.890431
    12.800000 0.877365 0.974897
    12.900000 0.864299
    13.000000 0.851232
    13.100000 0.839822
    13.200000 0.828411 0.925448
    13.300000 0.817001
    13.400000 0.805590
    13.500000 0.794180
    13.600000 0.782769 0.876000
    13.700000 0.771359
    13.800000 0.759948
    13.900000 0.748538
    14.000000 0.737127 0.826552
    14.100000 0.728220
    14.200000 0.719312
    14.300000 0.710404
    14.400000 0.701496 0.793103
    14.500000 0.692588
    14.600000 0.683680
    14.700000 0.674773
    14.800000 0.665865 0.759655
    14.900000 0.656957
    15.000000 0.648049 0.742931
    15.100000 0.642464
    15.200000 0.636878
    15.300000 0.631293
    15.400000 0.625708
    15.500000 0.620123
    15.600000 0.614537
    15.700000 0.608952
    15.800000 0.603367
    15.900000 0.597781
    16.000000 0.592196 0.659310
    16.100000 0.590775
    16.200000 0.589355
    16.300000 0.587934
    16.400000 0.586513
    16.500000 0.585093
    16.600000 0.583672
    16.700000 0.582252
    16.800000 0.580831
    16.900000 0.579410
    17.000000 0.577990
    17.100000 0.577990
    17.200000 0.577990
    17.300000 0.577990
    17.400000 0.577990
    17.500000 0.577990
    17.600000 0.577990
    17.700000 0.577990
    17.800000 0.577990
    17.900000 0.577990
    18.000000 0.577990
    18.100000 0.577990
    18.200000 0.577990
    18.300000 0.577990
    18.400000 0.577990
    18.500000 0.577990
    18.600000 0.577990
    18.700000 0.577990
    18.800000 0.577990
    18.900000 0.577990
    19.000000 0.577990
    19.100000 0.577990
    19.200000 0.577990
    19.300000 0.577990
    19.400000 0.577990
    19.500000 0.577990
    19.600000 0.577990
    19.700000 0.577990
    19.800000 0.577990
    19.900000 0.577990
    20.000000 0.577990


    Figures supplied & Interpolated were
    Volts PSI
    0.000000 47.000000
    =================================
    0.400000 44.755000
    0.800000 42.510000
    1.200000 40.265000
    1.600000 38.020000
    2.000000 35.775000
    2.400000 33.530000
    2.800000 31.285000
    3.200000 29.040000
    3.600000 26.795000
    4.000000 24.550000
    4.400000 22.305000
    4.800000 20.060000
    5.200000 17.815000
    5.600000 15.570000
    6.000000 13.325000
    6.400000 11.080000
    6.800000 8.835000
    7.200000 6.590000
    7.600000 4.345000
    8.000000 2.100000
    8.100000 2.066793
    8.200000 2.033586
    8.300000 2.000379
    8.400000 1.967172
    8.500000 1.933966
    8.600000 1.900759
    8.700000 1.867552
    8.800000 1.834345
    8.900000 1.801138
    9.000000 1.767931
    9.100000 1.734724
    9.200000 1.701517
    9.300000 1.668310
    9.400000 1.635103
    9.500000 1.601897
    9.600000 1.568690
    9.700000 1.535483
    9.800000 1.502276
    9.900000 1.469069
    10.000000 1.435862
    10.100000 1.417759
    10.200000 1.399655
    10.300000 1.381552
    10.400000 1.363448
    10.500000 1.345345
    10.600000 1.327241
    10.700000 1.309138
    10.800000 1.291034
    10.900000 1.272931
    11.000000 1.254828
    11.100000 1.236724
    11.200000 1.218621
    11.300000 1.200517
    11.400000 1.182414
    11.500000 1.164310
    11.600000 1.146207
    11.700000 1.128103
    11.800000 1.110000
    11.900000 1.091897
    12.000000 1.073793
    12.100000 1.061431
    12.200000 1.049069
    12.300000 1.036707
    12.400000 1.024345
    12.500000 1.011983
    12.600000 0.999621
    12.700000 0.987259
    12.800000 0.974897
    12.900000 0.962534
    13.000000 0.950172
    13.100000 0.937810
    13.200000 0.925448
    13.300000 0.913086
    13.400000 0.900724
    13.500000 0.888362
    13.600000 0.876000
    13.700000 0.863638
    13.800000 0.851276
    13.900000 0.838914
    14.000000 0.826552
    14.100000 0.818190
    14.200000 0.809828
    14.300000 0.801466
    14.400000 0.793103
    14.500000 0.784741
    14.600000 0.776379
    14.700000 0.768017
    14.800000 0.759655
    14.900000 0.751293
    15.000000 0.742931
    15.100000 0.734569
    15.200000 0.726207
    15.300000 0.717845
    15.400000 0.709483
    15.500000 0.701121
    15.600000 0.692759
    15.700000 0.684397
    15.800000 0.676034
    15.900000 0.667672
    16.000000 0.659310

    Accurate choice of two there !

    FIC Inj Short Pulse adder
    Mix of two PCM tables

    Inj Pulse adder
    0.0 0.250 0.0 0.250
    0.06 0.236
    0.1 0.227
    0.12 0.222
    0.18 0.209
    0.24 0.195
    0.30 0.181 0.3 0.182
    0.36 0.167
    0.4 0.159
    0.43 0.153
    0.49 0.139
    0.5 0.136
    0.55 0.126
    0.6 0.114
    0.61 0.112
    0.67 0.098
    0.73 0.084
    0.79 0.029
    0.8 0.068
    0.85 0.057
    0.9 0.045
    0.91 0.043
    0.97 0.029
    1.0 0.023
    1.03 0.015
    1.09 0.001
    1.1 0.0
    1.16 0.0

    Interpolated data (LT1 table min division is 15.3uS)
    ====================
    488=139.2 == 137.2 0x09
    549=126.2 == 122.1 0x08
    610=112.0 == 106.8 0x07
    671= 97.5 == 91.6 0x06
    732= 81.2 == 76.3 0x05 *
    793= 69.3 == 76.3 0x05 *
    854= 56.0 == 61.0 0x04
    915= 41.6 == 45.8 0x03
    976= 27.6 == 30.5 0x02
    1037= 13.1 == 15.3 0x01
    1098= 1.0 == 0.0 0x00






    The 1st shows a really BIG difference in the injector PW on cold startup. about 2mS & 6mS initially. I noticed you are using some beta version 4.8 of eehack.

    Where did you get it. Last stable release was 4.7 , and I used 4.7 as a base for all mods I have done.
    It could be that this beta version has some bugs in the datastream.

    I suggest you to switch to 4.7 or the one I modified and try to duplicate that condition. It is weird because narrowband 02s are the same accross the banks and did not get lean, on the right side with that much fuel you should get a stall at cold start up.
    The 4.8 I think was from Steveo's site. This is on the PC in my office. The car is either running 4.7 or your 13_10_2018_v2 version.


    I suspect a bad injector on the right side also, you got intermitten lean conditions on the right side which resembles me the same conditions I got with an injector set that went in the trash bin.

    That random errors also suggest a bad wiring or bad pcm. You should check for melted wires around headers.
    If you look again, in the 2nd jpg, both injectors are around 5 or 6mS.
    This is on a bog stock Z28 tune.
    The fault seemed to be on the LHS

    A new PCM is on its way.

    What I find strange is that
    a: the O2's don't suggest anything odd but then they are still cold.
    b: How or WHY is the Injector pulse calculated differently for each bank ?

    I replugged/sprayed cleaner on the injector connectors between runs.

    On another note, Why don`t you get a 85mm truck MAF and give it a try. It is not that expensive and will support a lot more airflow. Delphi units goes for 70-80$.
    I never got that far with the tuning :-)
    I started tuning SD and this lean surge has never fully gone away unless I dump fuel into it.


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

  2. #32
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    Slope flow matching data: Average flow rate at 43.5psi = 428cc/min. Your set is Flow matched within 1.9%
    Injector offset matching data: Average offset at 3bar & 13.5V 962uS. You set is matched within 1.4%

    In my notes Fuel pressure at Idle with Vac hose off is 47psi (which is what the engine should see under WOT)

    **** So we need to use the 47psi injector kPa value ===
    1 psi = 6.89476 kPa
    47 psi = 324.05372 kPa
    The fact that they gave you a specific offset and static slope is promising.

    Unless you have an adjustable FPR I think I'd regenerate your data using 43.5 / 300kpa unless you have an overwhelming amount of faith in the accuracy of the gauge that 47psi was measured with. If it's a typical shop grade gauge that registers 0-100, a 3-5 psi indicator error along with a 3-5% linearity error is not unheard of. Here in the states we have the "miracle" of Harbor Freight which is a huge importer for extremely low grade instruments such as the one I purchased. Mine would read 46 psi on my 4 bar vehicles. Most troubleshooting guides will tell you a 4 bar system won't even start at 46 psi. I replaced the original junk gauge with a $20 liquid filled gauge from the hardware store and it reads in the relative neighborhood. But I still wouldn't use it as a calibration reference.

    I was more interested in the method you used for interpolation than the data. I'd really like to develop something that works in libreoffice. But that would probably be info better suited for a different thread.

    Good luck...

    Edit: Another simple check I would suggest is measuring your injector impedances from the PCM connector while having a helper jostle the harness around. This would tell you if all the injector leads in your harness are intact.

  3. #33
    Fuel Injected! Terminal_Crazy's Avatar
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    Hiya

    Quick update. I still have some weird shit going on...

    OK I've spent the afternoon recalculating the Offsets
    I recalculated IFC at 44.1 (47psi) which should be very lean from 38.51 (about 14%))

    I see what you save above, so can still pull it back to 42 later.

    I used the data of the website to recalc the Voltage Offsets.
    At 13.6V the difference is about 11.5% lower
    Reset the Low PW adder table

    I Flashed with Kur4o's 13_10_2018 EEHack 4.90
    I Have NOT altered the in car laptop to view the InjectorPW so didn't see the same issue as befor until I got the log up on my desktop.

    First start, by 86C had idle BLM's at 138 154 - not too shabby
    as it got hotter BLM's moved.
    141 154
    143 154
    144 154
    146 147
    148 148 OK
    went for short drive RH BLM 16 topped out at 160
    Trimalyzed data which really increased the low map areas up & went out again.

    Car ran OK and was generally happy
    Surge was still present but car did idle at 7mph quite happily.
    Surge came on as soon as increased throttle 1.2% and went off after about 15mph (8%tps)


    I might pick up some O2 sensors and replace them as well as checking all the grounds and cables etc.

    I still don't KNOW why the InjPW would be different in Open Loop ?



    Interpolation of data:
    I don't use MS Excel and my use of LibreOfficeCalc is limited
    I don't think interpolation is available as std. There seemed to be some extension available for Excel.
    The maths to fit curved data was well outside my field.
    I started to read an glazed over.
    So my program just uses linear interpolation.
    For day to day use I have ARM processor based computers as well as PC's and Linux boxes.
    My main computer runs RISCOS, written by Acorn from the original BBC micro back in the 80's who then went on to develop the ARM processor.
    For quick calculations I either use BBC Basic an easy & fast programming language or write programs in C/C++

    Anyways. for the interpolation, I take a data table such as
    0 5
    10 100
    decide how many points I want (say 5 across the columns and 5 between the rows )
    Precalculate the size of grid needed to fit the data in so i end up with
    0 x x x x 5
    x x x x x x
    x x x x x x
    x x x x x x
    x x x x x x
    10 x x x x 100

    Then move across the cells. Dividing the difference up as a fraction of the difference (5-0 =5. 5/5==1 ) so we get 0+1x1, 0+2x1, 0+3x1, 0+4x1, until we hit the next row
    I then calculate the next data row 10 to 100 so that is (100-10=90. 90/5 == 18 ) so we get 10+1x18, 10+2x18, 10+3x18, 10+4x18
    this gives me
    0.000000 1.000000 2.000000 3.000000 4.000000 5.000000
    x x x x x x
    x x x x x x
    x x x x x x
    x x x x x x
    10.000000 28.000000 46.000000 64.000000 82.000000 100.00000

    Then traverse the grid for each column which gives us
    0.000000 1.000000 2.000000 3.000000 4.000000 5.000000
    2.000000 6.400000 10.800000 15.200000 19.600000 24.000000
    4.000000 11.800000 19.600000 27.400000 35.200000 43.000000
    6.000000 17.200000 28.400000 39.600000 50.800000 62.000000
    8.000000 22.600000 37.200000 51.800000 66.400000 81.000000
    10.000000 28.000000 46.000000 64.000000 82.000000 100.000000

    IF you can explain how to calculate this any better to fit curved tables i'd be interested.
    As it is, each grid virtex (4 points) are plotted linearly onto a plane.

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

  4. #34
    Fuel Injected!
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    I see you are out of ideas, so why don`t you jump in and give it a try of the ls injector patch. Anyway you already have the needed cal data.

    When I put the ls injectors I figured that is not possible to interpolate the tables good enough, and since ls injector data is superior to anything gm have done previously I just made the patch to utilize the improved ls inj data.

    The PCM calculates how much air enters the engine in grams/second. Than slash that to the commanded AFR and find the needed fuel in grams/second.

    The grams of fuel needed are converted to inj pulse width with the help of engine rpm and fuel flow constant.

    So you need a dead spot fuel flow constant. It should be 43.5psi /3 bar at WOT, if it is other than that check your regulator or gauge.

    Than the PCM adjust the voltage offset. At lower voltage the injector don`t open fast enough and the pcm compensate for the less fuel flow by adding some ms to already calculated inj pulse width.

    Unfortunatelly the fuel flow of the injectors is not linear from zero. It gets linear after about 3-4ms range. Below that range they flow less in most cases and the PCM compensate by adding more ms to inj pulse width. The curve here is what matters most.

    If any of this components are not accurate you will get all kind of weird conditions running lean and rich at the same time under different engine loads that require the same pulse width.

    Tuning at this point is not possible.

    Tuning air tables through injector constants is really bad idea that should be avoided on all costs.

    Ve table should be smooth and linear accross the table. The ve value is interpolated almost anytime between 4 adjacent cells and you can jump from lean to rich really easy if the transition is not smooth enough. Maf is much easier to tune so you can give it a try. You should always tune VE and MAF at open loop until you match the commanded and the actual afr.

    At this point I can only suggest to start from scratch and do it all over again the right way. Tune everything in open loop and than switch to closed loop.



    On the right side I saw 02s drop to zero on several occasions with no apparant reason, suggesting bad injector.
    Don`t focus that much on inj pulse width, 02s give better idea what`s happening.

    I hope you can duplicate that inj difference at start up. In open loop the two sides must have almost identical readings. Some fluctuations are possible due to the data stream updates at different times accross banks.

  5. #35
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by kur4o View Post
    On the right side I saw 02s drop to zero on several occasions with no apparant reason, suggesting bad injector.
    Don`t focus that much on inj pulse width, 02s give better idea what`s happening.

    I hope you can duplicate that inj difference at start up. In open loop the two sides must have almost identical readings. Some fluctuations are possible due to the data stream updates at different times accross banks.
    I need to sort out this weird issue first.
    I hadn't seen the InjPW go to zero but when they match up they are much less stable than the lhs in the offset display.
    This seems to have started about 12 DEC and when I started playing with the EOIT so i'll try an earlier bin again that was ok.

    It's in about 7 of the last 14 logs. I need to adjust EEhack graph so it displays the PW taller

    Strange thing is, the car sounds and runs ok.

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

  6. #36
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    OK I've spent the afternoon recalculating the Offsets
    I recalculated IFC at 44.1 (47psi) which should be very lean from 38.51 (about 14%))
    Once again, why are you using 47 psi to calculate flow? Do you have an adjustable fuel pressure regulator?

  7. #37
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by spfautsch View Post
    Once again, why are you using 47 psi to calculate flow? Do you have an adjustable fuel pressure regulator?
    That was measured fuel pressure.
    I recalculated the voltage offsets with the online generic data rather than off the supplied sheet.
    Change from previous data was about 10-14% lower. IFR raised back to rated 42# an increase of about 14%
    I then recalculated offsets back at the 300kpa pressure and there were minor differences.

    Reflashed with EEHack 4.7
    Initial fire up was a bit rich, blm’s sat about 151-121 so I resloped the VE Tables.
    This change has brought the low corner of the VE table up quite a bit and doesn’t drop off like a ski slope now.
    Blm sat at 126-127.
    Needs a run out now.

    New pcm and o2’s are on their way.
    Issue withe InjPW seems to have gone so maybe just a wierd flash issue.

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

  8. #38
    Fuel Injected!
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    I got a little confused what you are trying to do.

    First you need that fuel flow figured. If you have the fuel flow at 42 pounds at 4 bar, you need to convert it to 3 bar flow.

    The formula is x*0.86602540378
    x= fuel flow at zero vacuum at 4 bar fuel pressure, [zero vacuum value should be the lowest value in the ls data].

    Than you have to convert the voltage offset. You should have a ls data table called injector offset vs vacuum vs volts . Take again the row at zero vacuum and interpolate to lt1 voltage . It will take some time but it can be done by hand easily.

  9. #39

  10. #40
    Fuel Injected!
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    For what it's worth, on every older LT1 I've measured, the fuel pressure has always been on the high side, usually 3-4psi higher than spec.

  11. #41
    Fuel Injected! spfautsch's Avatar
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    For what it's worth, I doubt you (or, more specifically Terminal_Crazy) was / were measuring with a recently calibrated, laboratory grade instrument. One can easily spend $300-$400 on such a device and it may still be off 1-3 psi "out of the box".

    My point is that I'm not sure I would skew all my injector data based on measurements taken with a $20-$50 instrument. And bear in mind a fuel injector "test kit" that sells for $50 likely includes a gauge that's worth about $5 and cost about $2. Just my $0.02, for what it's worth (considerably less than $0.02).

  12. #42
    Fuel Injected! Terminal_Crazy's Avatar
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    Hi all.
    A little update & reply to you all.



    kur4o
    I got a little confused what you are trying to do.

    First you need that fuel flow figured. If you have the fuel flow at 42 pounds at 4 bar, you need to convert it to 3 bar flow.

    The formula is x*0.86602540378
    x= fuel flow at zero vacuum at 4 bar fuel pressure, [zero vacuum value should be the lowest value in the ls data].

    Than you have to convert the voltage offset. You should have a ls data table called injector offset vs vacuum vs volts .
    Take again the row at zero vacuum and interpolate to lt1 voltage . It will take some time but it can be done by hand easily.
    The injectors are rated 42lb at 3 bar (50 at 4 bar).
    I understood we used the fuel pressure (which is measured from above atomspheric).
    So I had _measured_ fuel pressure at 47psi and used the 324.05kPa figures accordingly, not 300kPa (3bar) like I have now, see below.


    spfautsch
    that was measured fuel pressure.With a factory pressure regulator?
    All measurements are slightly more accurate guesses, gotta start somewhere.

    sherlock9c1
    For what it's worth, on every older LT1 I've measured, the fuel pressure has always been on the high side, usually 3-4psi higher than spec.
    spfautsch
    For what it's worth, I doubt you (or, more specifically Terminal_Crazy) was / were measuring with a recently calibrated, laboratory grade instrument.
    One can easily spend $300-$400 on such a device and it may still be off 1-3 psi "out of the box".

    My point is that I'm not sure I would skew all my injector data based on measurements taken with a $20-$50 instrument.
    And bear in mind a fuel injector "test kit" that sells for $50 likely includes a gauge that's worth about $5 and cost about $2.
    Just my $0.02, for what it's worth (considerably less than $0.02).
    Whilst I don't disagree with you, Not measuring it is no less a guess.
    The 47psi value converted to 324.053kPa
    I interpolated & used the data from 324.05_ so already ANY data is skewed.
    Enough to make a difference... unlikely.

    ....
    Anyway
    I reset the IFR to the rated 42lb
    Recalculated the Voltage Offsets to the 300kPa figure
    again Nothing quite matches the same with the generic data or the supplied data
    The values were slightly lower ( 1 maybe 2 hex values in each cell).
    NOTE: I suspect the VE table has a finer adjustment than the Voltage offsets themselves.

    By the time i'd dicked about with the VE table I'm pretty much back where I was before.

    I spent the weekend jacking tables around, anything air flow/mass related.
    The BLM's & VE were extremely rich
    I had the car running real nice, no surge BUT the O2's were averaging 500mV and the car stunk of fuel.
    Idle AFR was showing 14.5-15.5 and the fuel guage was moving faster than I was.

    I pulled the O2 thresholds to get the O2's averaging 450mV and sloped the VE Tables and voila, I'm back where I was again.


    I think I'll tidy the VE tables back up and try with the MAF.
    I also have another PCM (1995) rather than a 1997. Doubt that should be an issue?
    And some fresh O2 sensors.

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

  13. #43
    Fuel Injected!
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    I just want to make sure you are scaling the fuel flow correctly, since you talked about some interpolation.

    The forumla is {√new/old pressure}*old flow = new flow
    or divide new pressure by old pressure; square root the result. Than multiply with the old flow.

    As you can see 50lb/h at 4 bar are 43.3lb/h at 3 bar. So tha data might be wrong or the conversion.
    You need to find out at what pressure it is measured. The fluid used for measuring is also a big factor, some use n-heptane and steveo suggest a compensation factor of 1.035 if measured of n-heptane.

    Here is some intersting debate over fluids and equipment used for measuring and what effects they have.
    One guy noticed that 1degree celsius difference, changed the flow over 5%.

    https://www.eng-tips.com/viewthread.cfm?qid=117108

  14. #44
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    I pulled the O2 thresholds to get the O2's averaging 450mV and sloped the VE Tables and voila, I'm back where I was again.
    Does this mean you're back to seeing the weird differences in the injector pulsewidth from bank to bank? Or are you just saying the surge returned?

    What is your method for tuning VE, and how confident are you that your table is "close". It took me months to gather enough data with narrowbands to get mine to a point I felt good about it.

  15. #45
    Fuel Injected! Terminal_Crazy's Avatar
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    Hi
    Datasheet:TestFluid 16B @ 88-91F/32C
    Average Flow Rate @43.5psi = 428cc/min.
    432, 430, 430, 429, 427, 424, 425, 426

    428cc == 40.8Lb/hr Lower again!

    Fluid=16B ?? Dunno what that is atm.

    40.8 * 1.035 == 42.228 lb (I'm at 41.997)

    I'll try 42.228 ( saves as 42.230) I've 44.09, 42.385, 40.8

    I have just looked back at the previous log to see if the InjPW dropped low.
    Only on decel does it drop below 1.1 and only on slamming the throttle closed.

    What i can see now I've increased the scale in EEHack is some oscillation in the PW at low load.
    It's crossing map & rpm boundaries but could be the VE table not settled yet
    WB is 15.5 to 16.5

    I tried slowing down the O2 feedback recently but ended up with a slow rolling idle
    I'll have a play with those next.

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

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