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Thread: Underpowered/too lean?

  1. #11
    Senior Member rchuff's Avatar
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    ^^^ Spoken from the tuning God himself!!

  2. #12
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    Quote Originally Posted by rchuff View Post
    ^^^ Spoken from the tuning God himself!!
    rchuff, just noticed you're in Willow Grove; I'm on Pine Rd in Philly; Montco (Huntingdon Valley) is the other side of the street

  3. #13
    Senior Member rchuff's Avatar
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    ^^^Grew up in Huntingdon Valley on pine Rd.

  4. #14
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    We'll have to arrange a play date! I'm near Pine and Alburger

  5. #15
    Senior Member Cooter's Avatar
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    Hey Gunter, thank you for dropping in!
    I’m not sure what you’re trying to explain?
    I wasn’t suggesting the WB sensor can tell the stock ECM how much to adjust (I know the ECM can only read a NB signal in operation, the reason for the NB emulator from a WB sensor). I was explaining data logging with a WB sensor is better because the data you get to input in MLV is more accurate. That MLV would know how much to adjust the map it spits out vs. only knowing toadjust (and not by how much).

    Do I have that right?

  6. #16
    Senior Member rchuff's Avatar
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    It sounds like if you real don't know what you are talking about maybe you shouldn't be talking about it?

  7. #17
    Senior Member Cooter's Avatar
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    rchuff: You talking to me?

  8. #18
    Quote Originally Posted by Cooter View Post
    Hey Gunter, thank you for dropping in!
    I was explaining data logging with a WB sensor is better because the data you get to input in MLV is more accurate.
    With 6-7 data queries per second you are missing 50 - 90% of all ignition cycles. Taking this into account, swapping an qualitative analysis with a quantitative one will not really increase accuracy.

    The second point is that many people forget the goal of tuning the ECM: it's not to get a "good" map, the goal is to stop AFV from dangling around. AFV is based on EGO correction. EGO correction works perfectly well in the ECM, and a WB O2 will show an average lambda of 1.0 in closed loop, even with a bad map. But EGO correction is the key. A wildly floating EGO correction will lead to a wildly floating AFV, so limiting EGO correction is the main task to get a stable AFV. EGO correction is what the ECM assumes the map is off stoichiometry, however it is computed. The ECM does not really care about the mixture, except that it shall not get (permanently) lean or rich, but only from a qualitative point of view.

  9. #19
    Senior Member Cooter's Avatar
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    I see the point you are making and it's valid for sure. But not the part I was trying to explain to the OP.
    Of course, trying to tune CL with a WB won't do much. It's only looking for stoic and a NB does that fine, in CL.
    I'm talking about datalogging OL operation with a WB to get the OL map closer, faster.*

    You're talking the most important part. Getting the OL map perfect is the goal, yes. If your EGO correction doesn't have to correct, you'll be at perfect fuel inputs instantaneously (and where it matters). The CL map will always search for stoic (as it should) and clean, safe, running but at cruise conditions only. As long as it's not "always lean" or "always rich" you're good.


    * To your first point, You are saying that more data points is better than less-but-better data? I didn't know logging WB vs. NB slowed that down! The more you know.....

  10. #20
    You are fully right, if the ECM is running in OL only, there are no corrective actions applied, hence no data available except a lean - rich transition from the NB O2 sensor.

    My impression was the question aimed at if it's preferable to force the ECM in OL, next tune the maps using a WB O2, then go back to CL operations afterwards. I do not see a real advantage in such a procedure. There's a reason, WB O2 logging was added to EcmSpy, because we ran all these tests a decade ago, when trying to find out an easy procedure to adjust the maps. In the end, using the dynamic maps lead to faster results than anything else and tuning could be done in (halfways) real life rides.

    > To your first point, You are saying that more data points is better than less-but-better data?

    Well, it depends, IMO. The WB O2 controller is spitting out data much faster than the ECM, so they somehow must be correlated with each other. The ECM knows exactly when to evaluate NB O2 voltage to get the information it requires. Running the engine at 50 Hz will provide 40 ms between each ignition. I do not remember how many data packages are send during this period, but let it be only 2 - which one indicates the exhaust gas oxygen level correctly? This is just the "inter-ignition" gap. The ECM needs about 130 ms to emit one data packet, good for 3 ignition cycles. Which of these three is shown in the ECM data, and to which do the WB O2 data apply? To make things even worse, riding is a highly volatile process, which then adds more uncertaincies as the operating point is constantly changing. Sure, this all can be coped with on an EC dyno, but this is not what most people are willing to pay. Therefore, more digits do not necessarily mean higher accuracy, especially when the time frames are differing. It's just swapping one problem with another.



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