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Thread: Flex Fuel M156

  1. #1
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    Flex Fuel M156

    Does anybody have any clue where to adjust the stoich ratio of 14.7 for gasoline to Flex Fuel? I can?t seem to find any parameters that allow to adjust for flex fuel. I know it has been done before. Please point me to the right parameters to make the corrections.

    Merry Christmas everybody!

  2. #2
    Senior Tuner BackyardTurbo_FTW's Avatar
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    They sell flex controllers to add on but I really prefer to NOT use them and just make a custom tune for E85 (or whatever blend you are running)

  3. #3
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    I don?t plan on running the controller. I ran it before but car was unhappy adjusting to it. My plan is to have a custom tune but I was having trouble scaling the injectors last time. Also, any pointers on which parameters to adjust for E85? Advancing timing would be one what about lambda? 14.7 for stoich and 9.8 for E85 blend. How do I make that adjustment?

  4. #4
    Senior Tuner BackyardTurbo_FTW's Avatar
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    Leave stoich, there's no need to change that. Adjust the injector multiplier by the amount the LTFT is. Then work on the load tables to keep it from tripping limp mode

  5. #5
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    Quote Originally Posted by BackyardTurbo_FTW View Post
    Leave stoich, there's no need to change that. Adjust the injector multiplier by the amount the LTFT is. Then work on the load tables to keep it from tripping limp mode
    Just to ensure I got the steps correct:

    1) log LTFT at idle and driving around with stock injectors
    2) change to larger injectors
    3) log larger injector at idle
    4) adjust injector multiplier table to match stock injector LTFT percentage
    5) adjust load tables to prevent limp
    6) repeat 4&5 until finalized

    Once LTFT is tuned and car does not go into limo mode. I can then start to advance timing slowly.

    Correct me if I missed anything.

  6. #6
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    Do I simply adjust MAF when running E85?

  7. #7
    Senior Tuner BackyardTurbo_FTW's Avatar
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    I would install the injectors and put E in the tank if thats what you plan to run. Then drive it around easy a bit until the LTFT settles. Whatever that % is, adjust the injector multiplier by that amount. If the LTFT is within a couple percent after that, finish fine tuning trims with MAF scaling. Then work on load/timing etc after that.

  8. #8
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    Thanks! I?ll give it a go

  9. #9
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    What are the capabilities of the OEM fuel system on ethanol? E47? Full E85?

  10. #10
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    Quote Originally Posted by RYRO View Post
    What are the capabilities of the OEM fuel system on ethanol? E47? Full E85?
    From research, there are many full E85 with stock system out there without any known issues.

  11. #11
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    Quote Originally Posted by BackyardTurbo_FTW View Post
    I would install the injectors and put E in the tank if thats what you plan to run. Then drive it around easy a bit until the LTFT settles. Whatever that % is, adjust the injector multiplier by that amount. If the LTFT is within a couple percent after that, finish fine tuning trims with MAF scaling. Then work on load/timing etc after that.
    I tried everything mentioned above and the first night (53 degrees), car ran fine without adjusting too much parameters. Car didn?t limp nor throw CEL. Today, I drove it as it was and CEL keep coming on; displaying cylinder 1 misfiring. Also, I notice when CEL turns on, my commanded AFR becomes 20+. I tried all sort of load table, inject table, and timing but the misfiring keep showing up.

    Would you know what may cause that? Why only cylinder 1 and not other cylinders. I also noticed when car was running smoothly last night, my commander AFR was at almost 14 rather than my existing 12.5. I didn?t adjust anything, just running different fuel. Would the fuel make correction to my commander AFR?

    Any help would be great.

  12. #12
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    Quote Originally Posted by Fu03steveC63 View Post
    I tried everything mentioned above and the first night (53 degrees), car ran fine without adjusting too much parameters. Car didn?t limp nor throw CEL. Today, I drove it as it was and CEL keep coming on; displaying cylinder 1 misfiring. Also, I notice when CEL turns on, my commanded AFR becomes 20+. I tried all sort of load table, inject table, and timing but the misfiring keep showing up.

    Would you know what may cause that? Why only cylinder 1 and not other cylinders. I also noticed when car was running smoothly last night, my commander AFR was at almost 14 rather than my existing 12.5. I didn?t adjust anything, just running different fuel. Would the fuel make correction to my commander AFR?

    Any help would be great.
    So I checked cylinder 1 spark plug and it was fine but I changed it just to be sure. It was still throwing CEL for cylinder 1 misfiring and random cylinder misfire. I dug a bit more and here are the results:

    - Left injector multiplier alone, vehicle at idle will not display STFT percent and within 30 second, engine will start knocking and throw Cylinder 1 misfire code. AFR at idle reads close to 14.7 at both o2 sensors.

    - Increased the entire injector multiplier table by 15% from factory ECU setting. Engine idles fine throughout entire temperature range from cold to warm; no CEL. STFT was changing between -20 and -25 percent.

    My question is: is it normal for STFT AND LTFT to be around -25 when running flex fuel? My goal is to run E85 but currently sensor is reading E58. Seems like the richness of the fuel equates to flex fuel needing roughly 30% more than gasoline. Anybody with experience with this?

    Thank you,

    SF