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Thread: figuring small pulse correction from injector flow data

  1. #1
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    Default figuring small pulse correction from injector flow data

    Does anyone know for sure how to calculate small pulse correction from injector flow data like below? I'm running very low pulse widths on Lucas 120lb injectors and being off a little makes a big difference, so I had them tested. I'm guessing this is what needed using 2ms as an example is:
    since 2 is 20% of 10, 2ms should theoretically flow .0392 (.196x.2=.0392)
    .030 was measured which is 30.7% less than .0392
    so the correction at 2ms should be .614, because the table shows 2.0ms rather than .002 (.002+30.7% is .002614)
    does that sound right?

    vol/squirt
    ms cc
    10 0.196
    8 0.153
    6 0.111
    4 0.070
    2.00 0.030
    1.90 0.030
    1.80 0.028
    1.70 0.025
    1.60 0.022
    1.50 0.019
    1.45 0.018
    1.40 0.018
    1.35 0.018
    1.30 0.017
    1.25 0.017
    1.20 0.016
    1.15 0.015
    1.10 0.015
    1.05 0.014
    1.00 0.013
    0.95 0.012
    0.90 0.010

  2. #2
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    Default

    I know a lot of people in the past, including myself, have been looking for voltage offsets for the Lucas 120s. Here's what was measured by Jeff at Acceleronics at 35psi and Accel who markets the same injector under part number 74120.

    dead time 35psi Accel 43.5psi
    volts ms volts ms
    8 1.26 8 1.364
    9 1.00
    10 0.81 10 .997
    11 0.70 11 .808
    12 0.61 12 .732
    13 0.60 13 .654
    14 0.57 14 .742
    15 0.48 15 .691

  3. #3
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    Default

    What part number are those injectors?

  4. #4
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    Default

    01D134B or 01D136B

  5. #5
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    That's a low impedance injector. Are you using an injector driver box or an aftermarket ECU?

  6. #6
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    e38 with a Versafueler injector driver

  7. #7
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    Does the engine have a functioning MAF sensor?

  8. #8
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    Its disconnected at the moment so the vve table can be tuned. The maf also needs to be tuned. This is turbo car with a 225 238 cam and 100mm maf not in the original location, so I don't have any accurate tables to extrapolate from if that's what your thinking. I wish I did because the small pulse adjust graph I end up with looks like a mountain range. The numbers Jeff at Acceleronics came up with for the voltage offset seem similar to what Accel has, when taking into account the different pressures. Because of that, Im going to assume the slope numbers are right but I would never have expected the flow from these injectors, or any really, to be so far out of whack. Time has to be added everywhere but the worst spot is at 1.5ms where it needs to be increased by 55%. That seems impossibly far off.

  9. #9
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    That's an unusual choice of cam for a turbo engine.

    Yeah, you can get some strange results when you try to calculate small pulse from a vve table which isn't exactly right.

    I might be able to help you with this... send me a PM.

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