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    Vishnu Flex Fuel

    So my GSXR1000 is sold as of tomorrow which means money coming back into the 'Toy Slush Fund'.

    At this stage my 135i has dci and a procede, with 7" fmic and downpipes ready to go on. I was thinking that my next major purchase will be a flex fuel kit. But first I have questions:

    1) Since the Standard DME already targets lambda the backend flash should take care of the fuelling requirements of running whatever fuel is available. So is the procede just using a modified table for timing and boost dependant on what the ethanol content is?

    2) How many many points are mapped for boost and timing? Eg boost and timing changes are mapped per 5% change in ethanol. So at e10, e15, e20 etc or is it not that refined?

    3) Over in the 335i forum there was a lot of talk about new flex maps but I haven't seen anything eventuate. Are these still being worked on?

    4) How much torque can my stock 6mt clutch hold? Will it hold up with my current mods. FBO less meth and on stock turbos.

    5) Has anyone here tried this out yet?

    I know not everyone is a fan of Vishnu, but I am not aware of any other ECU that can control Timing and Boost based on Ethanol content.

    Thanks
    David

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    Unless you're getting bigger turbo's the stock fuel system should be fine with E50.
    Stock 6mt will be fine as well (up to 500whp/500wtq)

    Not sure about the backend flash question, Email shiv.
    The maps are not targeted on ethanol content. You will get one map for E50 (my guess).




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    Does it control timing and boost based on % of ethanol?

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    An ethanol sensor is nice in theory but the procede mapping is pretty simplistic. The procede holds two maps. The ethanol sensor is then programmed as a 0-100% variable which averages the values between those two maps. So there is a linear mapping of boost target A to boost target B, CPS offset (not timing) A to CPS offset B, o2 bias A to o2 bias B, and fuel pressure bias A to B. But the tuning is not smart enough to monitor knock, monitor fuel trims, and adjust it's mapping as needed. And there lies the issue. There is a non-linear relationship between ethanol content and tuning variables. The changes from 0% ethanol to 10% ethanol is different than from 70% ethanol to 80% ethanol. So the system is inherently flawed and over simplified. I just can't justify the high cost of the sensor and install headaches personally. It's interesting data to have but it's just not that useful if the tuning is setup properly.

    The JB4 handles things differently but since this is a procede thread I won't offer a sales pitch. But as a general piece of advice with the procede I'd skip the flex fuel sensor and simply tune the car for E45, and make sure you run E50+. Use their back end flash as well. You can load it for free with BB software. The DME itself can handle fuel trim variances of 15-20% E85 variances so that won't be an issue. At greater than 60% E85 you run in to high pressure pump problems. So 50-60% E85 is the sweet spot anyway.
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    An ethanol sensor is nice in theory but the procede mapping is pretty simplistic. The procede holds two maps. The ethanol sensor is then programmed as a 0-100% variable which averages the values between those two maps. So there is a linear mapping of boost target A to boost target B, CPS offset (not timing) A to CPS offset B, o2 bias A to o2 bias B, and fuel pressure bias A to B. But the tuning is not smart enough to monitor knock, monitor fuel trims, and adjust it's mapping as needed. And there lies the issue. There is a non-linear relationship between ethanol content and tuning variables. The changes from 0% ethanol to 10% ethanol is different than from 70% ethanol to 80% ethanol. So the system is inherently flawed and over simplified. I just can't justify the high cost of the sensor and install headaches personally. It's interesting data to have but it's just not that useful if the tuning is setup properly.

    The JB4 handles things differently but since this is a procede thread I won't offer a sales pitch. But as a general piece of advice with the procede I'd skip the flex fuel sensor and simply tune the car for E45, and make sure you run E50+. Use their back end flash as well. You can load it for free with BB software. The DME itself can handle fuel trim variances of 15-20% E85 variances so that won't be an issue. At greater than 60% E85 you run in to high pressure pump problems. So 50-60% E85 is the sweet spot anyway.
    Hmm, that's somewhat disappointing. I assumed it would work the same way as my brothers Evo. I know when he was setting that up, it was no where near a linear relationship between timing, boost and ethanol content.

    Feel free to throw the Sales Pitch, its more of a Flex Fuel thread than a Vishnu thread. Ethanol fuels aren't readily available everywhere over here yet, hence my interest in flex fuel as opposed to a single E% map.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    An ethanol sensor is nice in theory but the procede mapping is pretty simplistic. The procede holds two maps. The ethanol sensor is then programmed as a 0-100% variable which averages the values between those two maps. So there is a linear mapping of boost target A to boost target B, CPS offset (not timing) A to CPS offset B, o2 bias A to o2 bias B, and fuel pressure bias A to B. But the tuning is not smart enough to monitor knock, monitor fuel trims, and adjust it's mapping as needed. And there lies the issue. There is a non-linear relationship between ethanol content and tuning variables. The changes from 0% ethanol to 10% ethanol is different than from 70% ethanol to 80% ethanol. So the system is inherently flawed and over simplified. I just can't justify the high cost of the sensor and install headaches personally. It's interesting data to have but it's just not that useful if the tuning is setup properly.

    The JB4 handles things differently but since this is a procede thread I won't offer a sales pitch. But as a general piece of advice with the procede I'd skip the flex fuel sensor and simply tune the car for E45, and make sure you run E50+. Use their back end flash as well. You can load it for free with BB software. The DME itself can handle fuel trim variances of 15-20% E85 variances so that won't be an issue. At greater than 60% E85 you run in to high pressure pump problems. So 50-60% E85 is the sweet spot anyway.
    I figured it was CPS offset the Procede would have to have the ability to flash to really change timing right?

    So it just loads different two different maps based on what the sensor detects.

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    Since you already have the procede my advice is first do their back end flash. Then setup your first map to function as a pump gas map and your second map to function as en E40 map. And toggle them manually as needed.

    On the JB4 end we use an auto tuning strategy where we infer the ethanol content from fuel trims and octane levels from medium term timing trims. The N54 DME is a fairly sophisticated animal compared to say an Evo. Fueling & advance are both closed loop systems with short and long term trims. Just get the tuning in the ballpark and it will handle the rest. But the right tuning can adjust things in the background so the DME is never out of range.
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I figured it was CPS offset the Procede would have to have the ability to flash to really change timing right?

    So it just loads different two different maps based on what the sensor detects.
    The CPS offset is applied globally to the crank position sensor to "fool the dme" to rescale advance, but also effects valve timing, fuel injection timing, etc. So it's sort of a catch-22. You can move it a little but too much causes unintended consequences. The JB4 does it too if enabled and its been discussed to death for years. But needless to say I'm just not a big fan. Switching "timing" between two vastly different maps on the fly though is probably the only thing CPS is really good for at least in theory. But with the right auto tuning strategy I just don't see the benefit in practice.
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    An ethanol sensor is nice in theory but the procede mapping is pretty simplistic. The procede holds two maps. The ethanol sensor is then programmed as a 0-100% variable which averages the values between those two maps. So there is a linear mapping of boost target A to boost target B, CPS offset (not timing) A to CPS offset B, o2 bias A to o2 bias B, and fuel pressure bias A to B. But the tuning is not smart enough to monitor knock, monitor fuel trims, and adjust it's mapping as needed. And there lies the issue. There is a non-linear relationship between ethanol content and tuning variables. The changes from 0% ethanol to 10% ethanol is different than from 70% ethanol to 80% ethanol. So the system is inherently flawed and over simplified. I just can't justify the high cost of the sensor and install headaches personally. It's interesting data to have but it's just not that useful if the tuning is setup properly.

    The JB4 handles things differently but since this is a procede thread I won't offer a sales pitch. But as a general piece of advice with the procede I'd skip the flex fuel sensor and simply tune the car for E45, and make sure you run E50+. Use their back end flash as well. You can load it for free with BB software. The DME itself can handle fuel trim variances of 15-20% E85 variances so that won't be an issue. At greater than 60% E85 you run in to high pressure pump problems. So 50-60% E85 is the sweet spot anyway.
    But... flex fuel sensor and APPROPRIATE mapping (one that takes into account the actual variance between various ethanol percentages) works correctly... correct?.. or how we hope the proEFI to work haha

    most other vehicles with much simpler ECU's can handle it the good way correct?

    it means you could have an E85 map for guaranteed E85... fill up a partial tank of 98 if you're in a pinch.. or lower quality potential-E70-fuel if there's no true E85 nearby

    i can see the use still.
    boop

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    The CPS offset is applied globally to the crank position sensor to "fool the dme" to rescale advance, but also effects valve timing, fuel injection timing, etc. So it's sort of a catch-22. You can move it a little but too much causes unintended consequences. The JB4 does it too if enabled and its been discussed to death for years. But needless to say I'm just not a big fan. Switching "timing" between two vastly different maps on the fly though is probably the only thing CPS is really good for at least in theory. But with the right auto tuning strategy I just don't see the benefit in practice.
    Yes I'm well aware I posted this a long time ago and Shiv had no response:

    Click here to enlarge

    To truly have timing control that adjusted based on ethanol content I don't see how it can be done without flashing the ECU.

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    Terry your flexfuel option is basically tuning boost and open loop based on trims correct. Can you explain more comprehensively how you autotune?

    The linear procede flexfuel mapping is the best approach, but a little pricey I agree. Using 2 static maps with a matched flash base is a good option. Could also use map0 flash to make 3 maps giving enough options to cover 0 to 100% E85 without issue.

    CPS... this is a great tool for flexibility. The int VANOS mapping from the various tuning/tuners can range 5+ deg easily. It's a global offset, most often retard, which has very minor effects since int/exh timing and injection window is altered uniformly. No I wouldn't add 5deg of adv, but retard I see no issues and yes it's good to map your most aggressive timing targets through the DME. For past rare misfires (not CPS related in all cases), the calcs were revised and eliminated any issue.

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    1 out of 1 members liked this post. Yes Reputation No
    This is a good thread! I've learnt a lot about how the different piggy's 'auto-tune' for E85 mixes.

    Maybe once the BB flash is released I might backend flash and give 50% E85 mix with 100% meth a go.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    It's a global offset, most often retard, which has very minor effects since int/exh timing and injection window is altered uniformly
    Anyone who says this doesn't understand just how of how BMW sets up the factory tuning is based on knowing where true dead center is. Defending CPS offset as timing control when it isn't is just plain stupid.

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    Sticky, you don't understand the tech parts here. Injection timing is based on valve timing so there's effectively no change here. Int VANOS at the same loads can vary a lot between the different flash tuning including with, without piggy. Keep in mind you are only retarding 5deg at the most. What does change is exh VANOS from the tuning "norms" but minorly (synced with int of course). VANOS is kinda an untouched parameter in experimentation and we have a large window to play with. There's little effect on tuning, besides potentially a couple hp in either direction.

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    I have the Flex Fuel kit and I do love to hear the back and forth discussion on this. I have to ask, again, why Koenigsegg is also using this type of fuel sensor option (detecting fuel before it enters the injectors) instead of using a more sophisticated DME. What I like is the ability to completely change my ethanol content wildly between tanks, without doing anything to the piggy, and having an appropriate (this is debatable based on how the maps are done and whatnot) map for the ethanol content detected.

    Of course, how the tuning must be done, perfectly, is non-linear compared to ethanol content, but wouldn't a linear approximation get somewhere in the ballpark? Of course, you could perfectly tune for a certain ethanol content, but doesn't that restrict you to only filling up certain ethanol percentages? Additionally, how do you know the ethanol you're getting is truly, say, 85%, instead of 70-90%?

    Could having a flex fuel sensor + a non-linear correlation be a perfect solution for an E85 setup, in general?

    I'm not strongly biased one way or another, but I do come from the background of having seen some inherent advantages to accepting a slightly flawed-for-the-ethanol-content tune in exchange for the convenience of seeing measurable horsepower gains that roughly correlate to how much ethanol is in the engine. To me, aside from the occasional rough idle and cold throttle application issues, I am loving this setup. Maybe you can explain, in more detail, how you can still retain this kind of performance/convenience without a fuel sensor. I am only asking because I am relatively ignorant about how this performs compared to alternatives.
    Last edited by Ferruccio; 08-15-2013 at 06:27 AM.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Sticky, you don't understand the tech parts here. Injection timing is based on valve timing so there's effectively no change here. Int VANOS at the same loads can vary a lot between the different flash tuning including with, without piggy. Keep in mind you are only retarding 5deg at the most. What does change is exh VANOS from the tuning "norms" but minorly (synced with int of course). VANOS is kinda an untouched parameter in experimentation and we have a large window to play with. There's little effect on tuning, besides potentially a couple hp in either direction.
    All I don't understand is why you are advocating CPS offsetting when so many of the BMW systems rely on knowing where true dead center of the crank is. So if you are manipulating, NOT ADJUSTING, timing in this way you are also setting yourself up for misfires and other codes. What do you think the VANOS system uses?

    I think you don't understand personally. Saying there is little effect on tuning when literally everything is offset makes no sense to me. Especially considering tuners with some serious BMW talent have told me differently.

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    I’m not going to argue with you. It’s a good tool and there’s NO negative effects if implemented correctly. All you know is that timed engine parameters are based on CPS and offsetting it is manipulation… when working with an OEM ECU often multiple functions are manipulated… piggys are known to do this, BUT flashes do it also. As long as you know what and how you are altering, and in some cases disabling, functions you can have a system that works well.

    I’m not advocating using CPS offsetting in all scenarios. Most often its used to reduce a tunes aggression, which is much better than the alternative. Its not a necessity but sure is convenient.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    I’m not going to argue with you. It’s a good tool and there’s NO negative effects if implemented correctly. All you know is that timed engine parameters are based on CPS and offsetting it is manipulation… when working with an OEM ECU often multiple functions are manipulated… piggys are known to do this, BUT flashes do it also. As long as you know what and how you are altering, and in some cases disabling, functions you can have a system that works well.

    I’m not advocating using CPS offsetting in all scenarios. Most often its used to reduce a tunes aggression, which is much better than the alternative. Its not a necessity but sure is convenient.
    That's fine because I'm going to argue with you. Saying it's a good tool when BMW's own documents tell you it isn't says enough, doesn't it?

    You don't know what and how you are altering everything. You're altering the VANOS, you're altering misfire detection, you're altering everything based on the ECU knowing where TDC is.

    I'm not saying CPS offsetting will kill baby seals and melt the icecaps but...

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    That's fine because I'm going to argue with you.
    Click here to enlarge

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    A few things here I'd like somebody that know to answer. The DME has to use the Crank and Cam sensors to figure out which Cylinder it's currently working on, which one is it relying on for timing, and is it relying on the same one for timing and vanos? Is it possibly it's getting timing from the Crank and vanos timing from the Cam, in which case the vanos wouldn't be affected?
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    Click here to enlarge Originally Posted by brusk Click here to enlarge
    A few things here I'd like somebody that know to answer. The DME has to use the Crank and Cam sensors to figure out which Cylinder it's currently working on, which one is it relying on for timing, and is it relying on the same one for timing and vanos? Is it possibly it's getting timing from the Crank and vanos timing from the Cam, in which case the vanos wouldn't be affected?
    I don't know but from what I see here and what a tuner told me seems the CPS and the ECU knowing where TDC is plays a rather valuable role with VANOS:

    For the purpose of instruction here, we'll assume that you have your cylinder head installed on the engine block, the crankshaft is locked at Top Dead Center (TDC), and your two camshafts are locked using the BMW camshaft locking tool. This article will guide you through the process of retiming your camshafts, and re-installing the Vanos variable camshaft timing unit.
    http://www.pelicanparts.com/bmw/tech...aft-timing.htm

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    I don't know but from what I see here and what a tuner told me seems the CPS and the ECU knowing where TDC is plays a rather valuable role with VANOS:



    http://www.pelicanparts.com/bmw/tech...aft-timing.htm
    I see the TDC coming in to play when physically setting the CAM timing but when it comes to the actually VANOS cam Phasing I would think that the cam sensor might be used. But it could be using the cam sensor for referencing which cylinder is on which cycle and using the crank for the exact timing but I still think that there's a possibility that either the cam sensor or just a hard codes PWM could be used for phase the cam and the VANOS timing might not be affected. Curious to see if anybody had dug that deep into how the DME works.
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Terry your flexfuel option is basically tuning boost and open loop based on trims correct. Can you explain more comprehensively how you autotune?

    The linear procede flexfuel mapping is the best approach, but a little pricey I agree. Using 2 static maps with a matched flash base is a good option. Could also use map0 flash to make 3 maps giving enough options to cover 0 to 100% E85 without issue.
    I'm a bit too lazy to get in to it at least at the moment. But as a short answer knowing the actual ethanol content itself is not overly useful. It's just half of some equation that you don't have the other half of. Just because you know you have E38 in the tank doesn't tell you how to set the fuel trims, advance, boost, etc, for your car, climate, and conditions. But what is useful is monitoring your fuel trims and adjusting fuel biasing so they always stay within a safe range, and monitoring knock activity and adjusting your timing & boost such that it stays within a safe range.
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  24. #24
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    All I'm going to say is many modern flexfuel vehicles do not use ethanol sensors. Multiple O2 sensors and actively monitoring fuel trims can tell you everything you want to know about your fuel.

    If you know fuel pressure, temperature and injector pulse width you can calculate your injected fuel mass. If you have a mas air flow sensor or MAP sensor with accurate VE maps you can calculate air mass. If you have a wideband O2 sensor you can calculate lambda, and thus get an accurate air:fuel ratio. From this you can calculate the engergy content of the fuel. Since you now know mass of air, mass of fuel, lambda, etc... and since you know you are only running gasoline or ethanol... you can calculate ethanol content.

    Ethanol sensors are circa 2000's. This is 2013. Get with the program guis.

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    Some interesting info from Vishnu on this same topic/thread here.

    http://www.1addicts.com/forums/showthread.php?t=877168

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