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Thread: Injection Mode Strategy & Stable Burn

  1. #1
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    Injection Mode Strategy & Stable Burn

    I'm probably wasting my time, as with the previous questions I posted a few weeks ago, but here goes:

    What is all this?
    The "Enabled Modes" per the enabled chart don't match what the #'s in the Stable Burn or Strategy charts have in them. Per the modes (upper right), Homogeneous Lean is Off, is it not? At the bottom of the page it says Homogeneous Lean is Bit 1, but many of the cells in the Stable Burn and Stragety charts have a 1. Help me understand...
    Then there's the 64 & 65 #'s in the charts. Wth are those? I can only "assume" they mean both bit 6 & bit 4 or 5 are active? Can two be active at the same time?
    Bit 6 is Homogeneous Split Injection, per the description. Bit 4 is Stratified Cat heating, which is disabled per the Enabled Modes chart. So does a 64 just = 6 then?
    65 would be a 6 & 5, but what is 5? It's not listed at the bottom. Not that it's enabled anyway.

    I'm messing with it because my idle shifts into a different mode after 10-60 seconds, and that mode is leaner. I don't know how, why or what that mode is, only that it exists.
    Playing with the #'s in the charts is not working out for me. It does do something, but not what I expect, or want, and so far only makes things worse. Worse being rough idle or an even leaner condition.

    Like so many things here it's more of a cryptic puzzle with no explanation. Anyone know wth is going here, or how to decrypt the values?

    Strategy.jpg
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909

  2. #2
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    It took me a minute to make sense of this, but they're binary coded values. The value would be the total of 2^(bit number) for each you want to enable.

    For the 1's, bit 0 is enabled because 2^0 = 1.
    For the 64's, bit 6 is enabled because 2^6 = 64.
    Add those together and you get the 65's.

  3. #3
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    I would've never thought of that, but now that you pointed it out, I see it. Thank you!
    So I do have only the two modes, and it's either one or the other, or both if it's a 65; Homogenous & Homogenous Split Injection.
    I wonder how having both active works? I could only assume it's Homogenous but switches betwen Spilt and not when it feels like it? I'm probably wrong but it's all I got.
    I also wonder what Homogenous is, unless that's just a $5 word for normal operation, which is what I suspect. So I assume if I turn it off/disable the Strategy Table, it would simply be Homogenous at all times.

    In the end, it seems whatever is causing my fuel to go lean at idle is not here. Unless maybe it's going Stratified without me knowing it? Stratified would make sense, maybe, but it says it's not active.
    I dunno, pulling my hair out with all this...
    All I know for sure is setting the idle range from 65 to 64 or 1 doesn't solve my problem. It changes it, and once I thought it was fixed because it was fine for a day, but then it finally went lean with a vengence. I still have more variations to play with so we'll see.
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909

  4. #4
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    Once you start the car its in Catalyst Heating Maps, then it switches to other Normal(Homogenous) maps.

    As I always say "There are many maps not included in HPtuners" but HPtuners is perfect for anyone wants to add power.

    For the Lean condition you could try playing around with Sensor Bias but I would check for any exhaust leaks first.

    How much lean does it goes?
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  5. #5
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    On gas the trims go to ~+17 when this "mode" kicks in at idle. If I add ethanol, which it clearly doesn't account for in this mode, it gets worse as you'd expect. At 20% Eth the trims go to 25.
    Another odd part is a few months ago 20% Eth caused trims to go to ~20%, and it took 28-30% Eth to peg trims at 25.

    So right now, with my added 20% Eth, it'll idle fine when not in that mode, with trims averaging 0 but darting around +-5. Then after xx random time at idle my Injector PW suddenly drops 30-40% and trims ramp straight to 25 to compensate. It may do this the moment the O2's kick On during warm up, but usually not. Often I let it warm up for 5+ min and it never goes into that mode. Or I may let it idle after a drive to see how long it takes, and while that mode almost always kicks in, sometimes it won't. So I'm baffled as to what it is, and what triggers it. So now I'm playing with the different injection modes to see if that's the reason. No luck so far, but I have more to test.
    I will experiment with O2 Sensor Bias. The numbers give me the impression they are for the narrow band O2's, but we'll see.

    Thanks outlaw
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909

  6. #6
    Quote Originally Posted by chevota View Post
    On gas the trims go to ~+17 when this "mode" kicks in at idle. If I add ethanol, which it clearly doesn't account for in this mode, it gets worse as you'd expect. At 20% Eth the trims go to 25.
    Another odd part is a few months ago 20% Eth caused trims to go to ~20%, and it took 28-30% Eth to peg trims at 25.

    So right now, with my added 20% Eth, it'll idle fine when not in that mode, with trims averaging 0 but darting around +-5. Then after xx random time at idle my Injector PW suddenly drops 30-40% and trims ramp straight to 25 to compensate. It may do this the moment the O2's kick On during warm up, but usually not. Often I let it warm up for 5+ min and it never goes into that mode. Or I may let it idle after a drive to see how long it takes, and while that mode almost always kicks in, sometimes it won't. So I'm baffled as to what it is, and what triggers it. So now I'm playing with the different injection modes to see if that's the reason. No luck so far, but I have more to test.
    I will experiment with O2 Sensor Bias. The numbers give me the impression they are for the narrow band O2's, but we'll see.

    Thanks outlaw
    Same here. It seems like a higher inj slope value exaggerates the STFT more, as though the computer is okay with total fuel trim being high, but if you have LTFT dialed in at a low #, STFT goes even higher if that makes sense. I suspect there's a table we can't see that would fix this.

  7. #7
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    Schnell:
    That makes perfect sense and is the exact conclusion I came to as well. That + & - adjustment I did to Inj PW Mult was the clue I needed. So I started pouring over old data which revealed that mystery mode wants trims to adjust by 17% (on gas), regardless of any adjustment in Slope or Inj PW Mult. So before I messed with those it would idle with LTFT at +10, then mystery mode would push STFT to 7, which = 17 total trim.
    When I had either Slope or Inj PW Mult bumped 10% to zero trims, mystery mode bumped STFT trims to 17. Weird, but that's what I'm seeing.
    Ethanol made it worse because I increased my Slope. In this case it was an additional +13.5% on top of the 10 I had. The math doesn't add up at all, but the point is it made it worse, so now it wants trims to go up ~25.
    Remember I mentioned that 20% Eth, which I have in it now, changed nothing compared to 30% Eth I had in it two weeks ago? And with 20% Eth a few months ago, trims were more like 20. Well, the difference is I was lazy so I did not change the Slope for 20%, it's still set to 30% Eth! So Eth wasn't the factor, Slope was!
    It's also worth noting that with 28-30% Eth, and my Slope set for it, it rarely faulted out an O2. It was on the edge of faulting with STFT sitting at +25, but simply didn't fault out very often. Now with 20% Eth but my richer Slope, it's idling with slightly negative LTFT. So while I can't tell how much further than 25 it wants to go, I can only assume, based on more O2 faults, that it wants go further. So my guess is it wants to compensate for whatever negative LTFT there was. So if LT were -2, then I guess it wants to bump STFT by 27?
    I also mentioned it's almost always the #2 O2 that faults out. Well, #2 almost always has more neg LTFT than #1...

    Why all this is what it it I don't know, but this is a semi-win because apparently I just have to lower Slope by 10% to make LTFT sit at +10, and STFT in mystery mode should be <25. I assume 15-20 but time will tell. More importantly, not fault my O2's. Fingers crossed... This means I could, potentially, run 30% Eth without worrying all the time.


    I'll still play with trying to stop mystery mode, because lowering Slope is a bandaid fix. I'm still open the better bandaid fix of LTFT working at idle because that would easily make up the diff, plus LT can go to 60. Under Fuel/Oxygen Sensors I see a Long Term Fuel Trims section that HP claims turns LTFT On or Off based on Intake Air Temp? Clearly another mistake, so I assumed it meant water temp, because the #'s looked right for water and water makes sense. But they work at any water temp and any IAT, so I have no idea what it does, nor do I know how to turn it on at idle.

    I suppose if I hadn't messed with Slope at all, LTFT would simply compensate for everything and mystery mode would be a non-issue, no O2 faults and I'd be blissfully ignorant.
    The question in my mind is; what happens if one/both O2 does drop out, for whatever reason. I believe fuel would default to the Target map, with zero trim, which could easily be too lean for Ethanol. This fear is the real reason I have Slope bumped up. I can't say for sure it would default to the Target, but why wouldn't it? I've always assumed it takes some default mystery # somewhere x Inj Slope x Inj PW Mult / Target Lambda chart values to give fuel in ms. Then O2 Lambda feedback adjusts as needed to try and hit Target Lambda? So if the O2's fail it's reasonably good to go if your trims were normally 0. If I have trims at +10 as a bandaid for my mystery issue, then if the O2(s) drop out, I'm 10% lean.
    I also don't know if one faulted O2 will kill one bank, or the remaining O2 will drive both. I mentioned that usually when one O2 dropped out I couldn't tell, and that wasn't just idle but full load as well. But sometimes it was obvious, and those times I never loaded it, I'd restart the car to reset it. I don't know what causes that rough idle but I can only assume it's super lean. It'll idle fine with half the fuel, I've seen it, so it must be even leaner than that, or maybe it's upsetting it in another way. Like how a low battery caused misfires.

    Another likely drawback of letting trims do the work rather than Slope is I'd imagine fuel enrichment would take longer. The reasoning, in my mind; it has a map to follow, as described above, but will that 10% trim carry over from idle or cruise, or will it default to the map, then wait for the O2's to say richen it up? My guess is the latter. If so, then it would be lean for a moment. Not a big deal, but I noticed boost is pulled when timing is retarding, and timing retard is on a timer of 1.3sec. So if waiting on O2's causes a little ping, then you have to wait 1.3sec before it's allow full boost. Well, I assume it's 1.3sec from the start of retard, but maybe it doesn't start counting down until knock noise has subsided. If so, it could add 1-2 seconds to the 1.3 sec.

    Looking at all this old data, for hours, gave me a headache. Plus it's the last thing I want to do on a Sunday, but it's raining so it's that or participate in liberal agenda brainwashing. I mean Movies & TV...
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909

  8. #8
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    It worked. Lowering the Slope from .0210 to .0201 brought the STFT from pegged solid at 25 to ~20

    Now if I can only figure out how to prevent overboost from turning my turbos off... It was always on the edge of it but now that I bumped power a bit, I'm over the edge all the time and I lose my turbos every time I drive >: |
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909