BMW F800GS engine tuning

Discussion in 'Parallel Universe' started by DakarBlues, Dec 17, 2009.

  1. itsatdm

    itsatdm Long timer

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    The bike can and does run without imput from the oxygen sensor. Its purpose is to "sniff" exhaust and relay info back to the ECU so that fuel flow can be adjusted back to 14.7 when the bike is in closed loop (relying on its pre programmed maps.) http://www.autometer.com/tech_faq_answer.aspx?sid=1&qid=48

    Its range is limited, hence called a narrow band oxygen sensor. Twist the throttle and the bike goes to open mode and uses the other sensors on the bike to arrive at the proper A/F for the conditions. All the oxygen sensor and subsequently the ECU knows, is that the exhaust is outside the scope of measurement. It is all book learning on my part, but leads me to believe the A/F ratio under those circumstances are pre programed too, based on what those sensors are monitoring.

    In a dyno run, the bike is in open mode. Am I correct in my assumption that it is the signal downstream from the ECU that gets the adjustment?, that would be the only way to capture data from the 3 remaining sensors. An oxygen sensor would seem important on a dyno run to arrive at proper settings, yet you rarely see them posted. It still seems a coarse way to capture all the real world options.

    I believe the Auto Tune comes with a wide band sensor. The oxygen sensor detects exhaust deviations the stock sensors cannot. Seems to me that is pretty crucial, as it can make adjustments to account for wear and changes in injector flow rates, such as partial blockage. Depending on the adjustments, it is possible all readings would be outside the range of a stock sensor.

    My beef with the stock ECU is that transition from 17 to 1 at warm idle to something usable when the engine spools up. At cold idle it will be something richer. I assume a Dynojet mod, will be richer yet.

    Maybe some one with more knowledge on what/how a Dynojet is adjusting, would convince me there is no downside to it.
  2. mousitsas

    mousitsas Long timer

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    There is really no downside provided it is tuned right, which is not trivial, but it is however fun. The autotune module works on a given AFR map in respect to rpm and % of throttle. As long as the operator knows what to do, it can be an amazing tool giving a much better result than any dyno ever can. Adjustability is infinite (almost).
  3. mapa63

    mapa63 Bikerider

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    Lots of good input here!

    Two published maps for the PCV and the F8GS, to begin from. It's Dynojets. The Zeromap, is mapped Zero for both cylinders, but individually. The other maps have the same settings in one table that is intended for both cylinders. The first map is for stock everything and the other one for Akra NoDbk and stock/aftermarket airfilter. Please feel free to comment! :D

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  4. itsatdm

    itsatdm Long timer

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    Does Auto tune change the values while riding on the bike? or produce a mapping tool to be used later to fine tune.

    The reason that I think it may matter, is the sensors that dictate which "map", are the position of the throttle, oil temp, air pressure(altitude) and air temp.

    The ECU reads electrical current from each sensor, does it computer thingy and sends a signal to the injectors that result in the proper opening time and pressure.

    My understanding is, this output is what gets changed by Dynojet. Add a little, lose a little. Correct?

    The maps are really mathmatical logarithms. Don't know much about them either, except they are the product of other numbers multiplied together, usually a square root. If so, they are weighted, depending upon the multiplier.

    Here is what I suspect. A perfect tune at sea level will not be perfect at altitude. What I do not know is if those sensors have some hierarchy of importance to the ECU. In other words is air temp more important than air pressure and is weighted more? The stock ECU makes adjustments and the output is the result of all the sensors product.

    Probably no worse result than fiddling with jetting on a carbed bike, but I am not sure it is as accurate as the stock ECU.
  5. ebrabaek

    ebrabaek Long timer

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    Last I saw it, it was on a Pikes peak Honda crf-450...... It was equipped with a PC-5 with AT. The tuner build a map based on what he thought best, using the dyno in the process. The varying a/f ratio at different throttle settings. Where the AT is it's weigh in gold..... Is the fact that it allows the individual rider/owner to customize the map which is the applied in wide band mode. So there is some programming to do, but with a stock dyno capture with the dyno's O2 sensor deep in the pipe, you should have a good starting point. Then you open the AT control panel, and just sets the a/f ratios to where ever you like. The unit runs in Wide band mode all the time. In summery, as our fellow Athens rider said... When done right..... the possibility's are endless. I truly believe that you can make a stock replica, and just take out the lean 0-10% throttle, and eliminate the bunny hopping, and suffer no fuel penalty...... and then have another map for power.....toggle between the two, and you have gold ...and platinum.....:D My tuner in Denver verified this....... Getting close....
  6. itsatdm

    itsatdm Long timer

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    I am sure you are right. I just compare it to what Poolside is appearing to be doing. Modifying the imput signals to the ECU rather than the output.

    Any idea what the result of all this modifying to the F800 in HP or rideabilty? My only gripe is with the off idle fueling.
  7. ebrabaek

    ebrabaek Long timer

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    As it is my grip as well.... I think to the tune of 3-5 hp, but when I do mine.... or should I say when Sisneros Speed Works of Denver,CO does mine, I will start on the Economy map first...... I don't think he has worked on BMW's before, but he has plenty experience as engine tuner. His bikes took the title at PPIHC a few years in a row..... Perhaps I could be the Guinna pig, and other could follow along. He currently e-mails maps to his customers, so if we could dial in mine...... it would be an easy user install, as the maps would be close, except for the open exhaust I have/will have.
  8. mousitsas

    mousitsas Long timer

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    Without a doubt, the best way to remap is to reflash the ecu, but this is no possible to do with bmw as far as I know. In that way you can change everything and still keep the closed loop functionality. Thing is that the closed loop functionality is so crude to begin with (due to the low performance electronics used) that with a good map you don't have anything to loose.
    On the other hand, you could theoretically keep the PCV+AT in closed loop at all times, but you may feel a slight hesitation as they autocorrect at a less than ideal speed. The safest approach to do this would be to use PCV+AT only for high throttle inputs with a zero map elsewhere. In any case, AT to function properly requires a very good base map. This base map is produced following many iterations between PCV+AT. Eg, you start with a zero map on the PCV and the AT corrects it after a ride. You then merge the corrected map to the base map and you repeat having got know a better base map, and so on and so forth. At some point, the AT will no longer be correcting the base map. This will be your best base map so far, which you may use on open loop with the AT disnonnected, or on closed loop with the AT online.
  9. ebrabaek

    ebrabaek Long timer

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    Spoke with my tuner yesterday. He mentioned just that.... Instead of two maps.....Which you could do just fine...... He said use the zero map for base..... tweek the off idle, and then ride with the AT off.... Then when you need the power turn on the AT..... I might have to wait until taxes come back as I need to add the headers into the cost.
  10. mapa63

    mapa63 Bikerider

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    Hello!

    I don't get this? If you ride with the AT off, how is it supposed to "learn" and make the trims? If you just start it from a zero-map, would'nt it take rather much driving before the AT has optimized for power?

    Maybe I just don't understand....

    Best regards,
    Mats
  11. mousitsas

    mousitsas Long timer

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    Probably Ebrabaek meant PCV instead of AT.
  12. ebrabaek

    ebrabaek Long timer

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    With the at off , and the zero map installed.... It simply follows the stock map.... Less the o2 input... Which is not use much anyway. You can toggle between two maps as well.
  13. mapa63

    mapa63 Bikerider

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    Ok, I get it. But when will the AT learn and develop it's trims? Don't they get lost if you shut it down? And can one just shut it down? In the PCV you incorporate a setting if AT is present or not. Maybe it works anyway if U toggle the connection between the PCV and the AT or cut the power to the AT?

    Best regards,
    Mats
  14. ebrabaek

    ebrabaek Long timer

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    I am not sure about the details on the interference between the two units.
    I am guessing that since the pc-5 can run on itself...... You are just running on stock map... With the zero loaded. True that you do loose the o2 sensor...... But it is used very little practically so to speak. A rider at he f800 depot reported a 6 up gain , and 4 in torque. I do believe that was with stock headers.
  15. mapa63

    mapa63 Bikerider

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    Good info! You would'nt happen to have a link?
  16. mousitsas

    mousitsas Long timer

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    I seriously doubt that this is correct, since I expect the O2 sensors to be offline at WOT anyway.
  17. ebrabaek

    ebrabaek Long timer

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  18. mousitsas

    mousitsas Long timer

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  19. ebrabaek

    ebrabaek Long timer

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    I was referring to the OP.....
  20. betasigscoot

    betasigscoot Palaverer

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    Hey all, I just picked up both F800 cams off Fleabay for $100 :eek1 to try on the F658. They look good from the pictures & description, but I'll find out for sure in a couple days. I asked the local BMW shop if they could put a diff. map on the BMS-K, but they said the software won't let them. I guess I'll be trying out the Power Commander w/ autotune or some other fuel mapping software. I'm not completely sure it will work, as I haven't read anyone else trying it; but at $100, who could resist? More to come...