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Thread: MPI and basic "flex fuel" working on MQB 2.0

  1. #41
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    I was just checking that out!! I don't see timing change with the flex fuel but I'm excited that things are moving.

  2. #42
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    Yeah, from my own research it seems that the factory flex fuel implementation is for fueling correction only.

    There is some logic for octane adjustment, but I think it's only used to reduce spark-- like for the person who puts in 87 octane by accident etc.

    Might be a way to enable to 'adder' side of that, but either way, nothing that I've seen that links any of that to ethanol content.

    I suspect if it was...many other platforms would have this feature implemented already.

    Here's to hoping that one day HPT can add some extra logic to it for a spark adder table at least.

  3. #43
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    so I'm not fully understanding what each flex fuel box does and what to enable and what ones to keep disabled. any help explaining this would be great! Attachment 107470

  4. #44
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    Quote Originally Posted by this guy View Post
    so I'm not fully understanding what each flex fuel box does and what to enable and what ones to keep disabled. any help explaining this would be great! Attachment 107470
    Yeah, some of the labels are not very clear and/or confusing.

    Flex Mode: Enabled means "use sensorless algorithm", Disabled means "use physical FF sensor"

    Alt Fuel Ratio Enable: Enable means "use manual alternative fuel ratio". Basically with enabled, the value you set below will override anything from the Flex fuel logic and be a simple static value.

    Alt Fuel ratio is your "Manual" alternative fuel ratio. This works OK, but they have the value such that it does not display any decimal places....so it's nearly useless.

    One thing to note, is that "alternative fuel ratio" is different than "ethanol content". For example saying Alt fuel ratio of 30 means 30% E85.... which is actually E25.5, if that makes sense. They could easily re-scale this though to make it in terms of E content like we all work and think (this is how I set my XDF up).

    So back to the manual alt fuel content field.... 0=E0, 1=E85. You can actually input values in between (ie 0.3 for E25.5 as described above), but it will round the display to either a 0 or 1. I confirmed the actual functionality with my XDF.

    To enable flex fuel, with a sensor.... you need to Set "flex mode" and "alt fuel ratio enable" to Disabled.

    But unfortunately they did not include a switch to enable SAE PID 0x52 to see your live Ethanol content via VCM scanner or any other generic scanner.

    Basically, you can enable Flex fuel, but you don't have a way to see what it actually is (but it will still work correctly in the background), and you can use Manual Ethanol content but the way it's displayed is wonky and can't really verify what you typed in.

  5. #45
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    More good news, it looks like some logging parameters were added:

    Charge air pressure / desired (aka TIP or PUT)
    Wastegate position
    A new torque request on the ECU side
    A few others, but I think those are the main ones we've been waiting for.

  6. #46
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    Thank you Aaron for helping me wrap my head around all this. What about Lambda ratio and engine adaptation? are you enabling those?

  7. #47
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    Honestly I am not sure. Lambda Ratio sound like it may be a switch to activate the sensor-less flex fuel algorithm. But I have not yet tried that or got it to work.

    For a sensor based flex fuel, all you need are those 2 switches.

  8. #48
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    Made a new thread to continue the ongoing dialog of tuning these cars: https://forum.hptuners.com/showthrea...-Tuning-Thread

  9. #49
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    this is great work , im currently setting mine up too , what dead times and fuel injector constant did you use for the large bosch injectors , any info i have found is not relative to the pressure that these run on the low preesure fuel side

  10. #50
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    This is what I'm using for the 925cc PR injectors. They came with a 'flow sheet', but it doesn't even say what pressure they were tested at. Furthermore... I have no idea at what effective pressure the tables are set for etc. So I just did some ballpark math, it was decent enough.

    At high RPM WOT, my STFT does go pretty negative, so I could probably tweak it a bit more, but it's been close enough and have not gone back to revisit it.

    I think editing Fuel Mass Correction -> Correct Factor 4 can also be used to add/pull timing as needed to keep fuel trims close to 0.

    We have a decently active Discord channel if you'd like to join, to talk tuning and such.

  11. #51
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    Forgot to attach pic

    Capture.PNG

  12. #52
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    thanks ill give these a try hopefully this week sometime , i have the mpi active on the stock injectors , but need bigger now , what part number injector are you using ? i have bosch 0280158040, i think thats what is available in most kits . ye sure id like to join

  13. #53
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    Quote Originally Posted by Golf7r View Post
    thanks ill give these a try hopefully this week sometime , i have the mpi active on the stock injectors , but need bigger now , what part number injector are you using ? i have bosch 0280158040, i think thats what is available in most kits . ye sure id like to join
    I think they may have been ground off mine. There was some talk about the PR injectors have a different spray pattern/custom nozzle to keep the spray pattern narrow to spray properly with an open port flap etc....but that may be BS in order to charge for $$, I don't know.