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Thread: BLMs say rich, but WBO2 and NBO2 and surging all say lean - what gives?

  1. #31
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    Fixing all the error codes will be a good start est error means its probably not controlling timing the high map code could stop it even reading the map sensor and run off a default table like a lot of other ecus that just use rpm vs tps to come up with a default map value .do you not have a speed sensor either
    Last edited by delcowizzid; 07-25-2018 at 12:42 PM.

  2. #32
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    The error codes were all fixed a while back, I'm not getting any error codes since then. My bad for not getting back to y'all.

    I have no speed sensor.

  3. #33
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    I put a new header gasket in (2.5 hours, grrr), and went for a rip. Out of sheer misery, I just went fatter and fatter just to see what it would do. Within a couple blocks I could feel where the surging was, so I'd pull over, fatten the VE 5 steps, burn, and try again. We're looking at about 50% fatter in and around 30kPa. Here is the resultant VE Table so far, with lean surge almost all gone (this table is by no means final, I just needed to get out of the heat for today):

    18-07-25.jpg

    I'm also noticing not only did the BLMs never go over 128, once I restricted the BLMs to not go below, today I noticed the INT not going above 128. Interesting. I found a similar experience at https://www.thirdgen.org/forums/diy-...ped-128-a.html, so I looked through my own bin and turned the DFCO limits back to what was stock (I had previously tried to have them "off"). I have not tested this, so I don't know if it made a difference.

    For anyone else who stumbles upon this thread trying to make an 8063 $4D work, welcome. It's screwey. I'm still working on it.

  4. #34
    LT1 specialist steveo's Avatar
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    30kpa column is mostly in decel conditions on your engine, isn't it (or really light cruising), there are lots of conditions that can occur there.

    if it's going lean in that area, it's probably decel enleanment. try reducing or disabling decel enleanment. DFCO is sketchy on this engine, might want to just disable it until you get it running right, then bring it back in for heavier decel only.

    also try 5 degrees less ignition timing @30kpa (failing that try 5 more)

  5. #35
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    30kPa is light cruising. This is a Pontiac Firefly (a Chevy Sprint); it's quite small and only 2400lbs.

    I have some data to share, and I have some questions

    DATA

    I took everything that had anything to do with DFCO and max'd it out. I can only hope that it would actually turn off.

    dfco-shut-off.JPG

    I also changed the lowest two settings in Decel Enleanment to 25.1, as they were 37.6 and 31.4 respectively.

    decel-enlean-reduced.jpg

    I also changed the lower two O2 Voltage Thresholds as they were reading 0.030-ish and that didn't make sense to me, so I changed them to match the others.

    o2-voltage-thresholds.jpg

    Then I went for a drive.

    O2 reads rich, but there is lean surge. On a whim, I reduced the O2 Proportional Gains at the low end by half (0, 16, 32, 48, 64), tested, dropped them more, tested, then started working my way down in settings until I could get decent O2 readings, and a decent VE table.

    o2-prop-gains.jpg

    I like to think I'm dang good at Googlefu, and finding solutions to my problems, but I kid you not - the information that is out there on how this all works, or what or when to alter it is a challenge to find and/or understand. I don't speak HEX, I'm not an engineer, I really don't want a polysyllabic formula on -how- the calculations are done. I just want a simplified "nutshell" this is what you need to do when it goes like this."

    QUESTION Having said all that, have I got this statement correct?

    "If the O2 seems to be changing grossly, and you're getting lean surge but you're not actually lean, reduce O2 Proportional Gains."

    The new question I need to work through, is that now that the car is VERY driveable (if it were a carb, I'd be like "dang, that runs nice!"), the VE cells are now quite low.

    Way back, I adjusted the Injector Constant (BPW) to 115msec because I'm running 18psi on 61lb 350 injectors. This is what the calculators suggested.

    After the first initial drives, I raised the Injector Bias to 564.58 usec (stock was 396.73) for reasons that made sense at the time. It took quite some time to find what setting to make this, and I only found one web page that suggested if you raise the fuel pressure by 40%, raise the Inj. Bias by 40% (though it looks now like my math is suspect).

    QUESTION Theoretically, now I should reduce the Injector Bias until I'm seeing max VE around 90? But my VE table only goes up to 3200. How do I know that I still have enough injector duty-cycle a 5500? With these settings, I am getting a good 12.6:1 at WOT to 5200 (the farthest I've gone so far).

    Am I over-thinking this?

    QUESTION Am I looking at this right? Max VE Table RPM is 3200 at 110kPa (currently 76.95). The VE Adder table at 5600 rpm is 19.14. If that's added to the last VE table cell, then 3200's "76.95" plus the VE Adder at 5600's "19.14" is now "96.06." Assuming I understand this correctly.

    ve-18-07-26.JPG

    Thank you for all your help, I really -do- appreciate it.

  6. #36
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    Quote Originally Posted by SkinnyG View Post
    QUESTION Am I looking at this right? Max VE Table RPM is 3200 at 110kPa (currently 76.95). The VE Adder table at 5600 rpm is 19.14. If that's added to the last VE table cell, then 3200's "76.95" plus the VE Adder at 5600's "19.14" is now "96.06." Assuming I understand this correctly.
    The thing I don't get, is if the VE cells are supposed to be under 95 (90 is better), then how does that work if the tables stop at 3200, and I'm revving to 5500? I wouldn't need -less- fuel there, would I? The VE would HAVE to be higher than at 3200??

  7. #37
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    Max ve is at max torque

  8. #38
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    Today I reduced the Injector Bias by 20%, and increased the VE table by 20%, turned off PE, unlocked the BLMs from 128, and went for a drive. 20% brought the highest VE to 90.

    Had a slight surge at 2000 and 30kPa, but I got some good datalogging in. The INT was doing its thing, the BLM still went lean, but not so dramatically. Engine still ran pretty good. Corrected the VE table using BLMs, then zeroed everything in Decel Enleanment and drove some more. BLMs stopped working (I have since returned the DE settings to factory).

    Nevertheless, I still datalogged, but checked the INT History when I got home, and they were all very close to 126-128 themselves.

    This afternoon I've been playing with subtle changes to the Spark Table.

    I'm hoping that as the VE gets closer, and the INT and BLM is happier, I'll have less issues with surging. It -does- seem to be improving itself as I've datalogged and tweaked the VE table.

  9. #39
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    Got a PM suggesting the higher fuel pressure might be an issue.

    Which got me thinking, and looking back at the logs. It doesn't seem to find stoich at idle at all, which is the same VE value as light cruise at 2000rpm. As the PM'r suggested, it might not be able to run a low enough PW at such low fuel requirements.

    Since I changed to an external aftermarket fuel pressure regulator that can be vacuum referenced, I think I'm going to hook it the vacuum and see if that can help me actually run with lower VE values at the bottom of the table.

    I seem to recall reading of people having issues tuning with a vacuum referenced fuel pressure regulator, so I need to do some research to see what the issues are.

  10. #40
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    With vacuum set up, I get 12psi at idle, which should make the injectors happy. It "felt" a whole lot better driving around, but my BLMs weren't moving, so I just did some slight smoothing and tweaking of the table with only one drive today. Lots of family stuff to do this weekend, so I didn't get much driving in at all.

  11. #41
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    Did three more datalogs and tunes, and it's running a whole lot better. I had less and less surging with each tune, but this was mostly all light throttle.

    Note: The BLM Coolant Temp Thresholds are set from the factory at Min: 189° and Max: 0°. Don't change those to numbers that are logical (like I did - Min:0° Max:189°), or the BLMs will stop working.

    So far, then, hypothetically: The whole cause of my original question (this thread), may just very well be that 18psi is too much, the injectors lose their stability, and the O2 has a fit trying to correct it. Maybe?

    Thoughts?

    Feedback?

  12. #42
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    BLMs are currently 126 to 129s.

  13. #43
    LT1 specialist steveo's Avatar
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    why not disable closed loop and just add or subtracting fuel until it runs right, then go back with the wideband and fine tune a bit?

    i found that the ECM is so dumb that it'll go into closed loop if you cut the o2 wire off halfway, and wont even run abnormally or complain about it. i remember someone telling me the wire acts like an antenna or something and picks up false cross-counts so it thinks it's running right.

  14. #44
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    I cannot get this ECU to actually stop going into closed loop, but I can restrict both the INTs and the BLMs from going anywhere, and I've actually done really well by looking at average O2 voltage, and adjusting VE according to the O2 average. Any O2s in the 700's I changed the VE by 5. 600's by 4. 500's by 3. High 400's I changed by 2 or 1 depending. I could narrow it down pretty quick.

    I got it so reasonably close, that I enabled the BLMs and they were correcting -almost- to where I would have corrected anyway, so while it takes longer, it is working. When I first had it running, you could tell right away when it switched to closed loop because it fueled so differently. In fact, it was noticeable with the original stock 305 as well.

    Honestly, like you are saying, the computer is pretty dumb, so I don't really need to fret for accuracy +/-0.01 - it will work fine, and it will still be better than a carburetor. I already have it hot and cold starting better than it ever did.

    I can confirm what you heard - For a time I did have the O2 completely disconnected and just ran my WB to a gauge, and yet the datalog still showed O2 movement. Disconnected.

    With a few more datalogs in the mornings this week (104°F this afternoon - ugh), I'll have this good enough to leave it. It's a V8 in a Chevy Sprint, for heaven's sake. :)

    Hopefully my oil cooler arrives this week so I can drop the engine temp down a bit more, and then find some heat-shielding so my shoes don't melt from header heat.

    22382348_10159411622425537_2335639183444675106_o-480x270.jpg

  15. #45
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    Some minor tweaking this morning before it got too hot.

    Fattened the idle a bit, O2 numbers be danged, I want a stable idle. Good solid and reasonably low MAP signal here.

    Dropped a bit of Spark Advance where there appeared to be some vibration. Weird that it's a narrow rpm/map range, could be driveline issues? Dropping the timing a few degrees seemed to make a noticeable difference. I'm still running a LOT of timing at light throttle, and idling at 28° advance. It works, trust me.

    Posting the bins and such for anyone else who comes through looking for answers. Also uploaded the original bin I pulled off the factory chip. (Note: this may not be the latest bin, but it's close)

    Nutshell:

    I -think- dropping the O2 Proportional Gains made a difference.

    I -know- running an external and vacuum-reference-fuel-pressure-gauge made a significant difference, and really was no added challenge to tune.

    It's pretty darn reasonable to drive despite no VSS - all emissions are deleted, no spark adders, lots of tweaking to IAC, throttle-follower, stall saver, and decel-enleanment. It's pretty decent. At this point DFCO is still disabled.
    Last edited by SkinnyG; 08-11-2018 at 09:46 PM.

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