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Thread: Injector Voltage Offset and Injector Offset Adder tables

  1. #1
    Carb and Points!
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    Injector Voltage Offset and Injector Offset Adder tables

    Hey there guys..... kindof new to the forum, definitely new to posting here.

    I am a bit of a noob when it comes to tuning and I am stuck on the above mentioned tables.

    I had my car dyno tuned and it just wasn't right, power seemed down etc. So back story on my setup to clear the picture a bit. Stock bottom end LT1, LE1 heads and intake, CC503 cam, ASM 54 MM throttle body, headers etc. when I was getting things running after heads and cam swap, it seemed the factory injectors were causing me some issues with fueling, so per the recommendation of the tuner that I had look at the file, he said to go with some nice 30 pound injectors.

    I did this, put on some trickflow 30 pound units and it was dyno tuned shortly there after, but in looking at the tune file he didn't change any of the injector offset tables from factory and only thing changed was the injector flow rate.
    once I got it home it was running pig rich at idle, BLM's maxed to 160 on both sides.

    I contacted Trickflow/Accel for the data sheet on the injectors and I was able to actually download it from here https://documents.holley.com/accel_i...ons_150130.pdf

    So I took the table within this document, or the numbers within and placed them within the Injector Voltage Offset fields teh best I could and manually smoothed things out for the areas that weren't covered by the data sheet.

    I then see the offset adder table and I am confused as to whether I modify this from factory settings, as it looks to me like it is truly additive to the Voltage Offset numbers, but I could be wrong.

    Any help would be greatly appreciated as I did look for the subject but found no real answer at the end of the threads. Some said that most tuners don't mess with the offset tables but I don't think that is the right answer.

    thanks in advance

    Mike

  2. #2
    Fuel Injected!
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    Mar 2013
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    I doubt the injector offsets can bring blms to 160.
    It is either the tune or the inj flow rate, unless there isn`t any mechanical failure.
    You are running extremely lean but have to find is it false lean condition or there is an air leak in the intake or exhaust manifolds.
    Other possible reason is a clogged injectors.


    Get eehack and make some logs.

  3. #3
    Carb and Points!
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    Thanks and I appreciate the feedback on this. I do have eehack and logged the car to see the maxed out 160 BLM at idle, came down a bit off idle. I checked all the connections, vaccuum, etc on the intake didn't see or feel like anything was loose, but tightened down the ones that I could. so possibly there was a slight leak. I then checked the tune, as I hadn't looked at it after the dyno tune and it didn't seem quite right or at least I wanted to double check.

    Injector flow rate was correct, but voltage offsets were all factory settings and I figured that they needed to match the injectors so I started digging and got me to here.

    Before my initial post above, as noted, I changed voltage offset to match the injectors that were installed, but missed the adder table, I pushed the tune to the car and BLMS were equalized or at least ALOT better.

    I just want these fields to be right before I go any further with long logs, etc to bring things in right.

    So back to my original question and maybe a little deeper :) if I put in the injector offset data based on the chart provided from the manufacuture of the injectors, do I need to change the adder table, zero it out, or leave it factory?

    Once I have that correct I will do more logging to find if there is any other issues.

    Thanks again for the response.

  4. #4
    Fuel Injected! steveo's Avatar
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    leave the adder alone for now

    your injector constant might be a bit off too. the injector data sheet should be read carefully for what the test conditions are, and sometimes small tweaks are required

    is your fueling way off across the board or does it improve under load? id like to see a log for sure.

  5. #5
    Carb and Points!
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    Thanks Steveo..


    this is the only log I have right now after changing the voltage offset and adder remained the same as factory. I haven't driven it again, stuck in my garage at the moment.

    Attached is the eedata file and exported csv
    Attached Files Attached Files

  6. #6
    Carb and Points!
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    Ok went out and did a test.

    I loaded the original tune I pulled after the dyno tune. BLMs pegged at 160 at idle. Seemed to get better with a little throttle.

    Loaded a tune with just the voltage offsets changed and pulled the BLMs down to a bit more normal levels, little bit of a split but not so rich, but with throttle, no load BLMs tanked to 108.

    Definitely have a bit of work to do, at least I feel.

    Will post the logs when I am back on my computer.

    Thanks

    Mike

  7. #7
    Carb and Points!
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    here are the two log files.

    The BLM split has me a bit concerned and going to try and dig into that a bit more. some sort of leak on the right side it looks like.

    thanks in advance
    Attached Files Attached Files

  8. #8
    Fuel Injected!
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    http://www.gearhead-efi.com/Fuel-Inj...rison-Humidity

    This thread covers most of your issues. It is an indepth guide how to tune startup and idle on lt1 engine.
    The tune you have is garbage. Start all over again with fresh stock bin and work from there.

  9. #9
    Carb and Points!
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    thanks man for the response, not what I really wanted to hear, to say the least.

    Money pissed in the wind on a dyno, by a tuner that has been doing it for years.

    Anyway will check out the thread.

    Appreciate it.

    FWIW.... you may of saw on the logs changing the offsets changed the BLM's alot.

    Mike

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