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

  1. #16
    LT1 specialist steveo's Avatar
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    Quote Originally Posted by SkinnyG View Post
    Am I understanding you correctly in that I tune so the computer/BLM is happy with whatever the end result it?

    Could I just change the listed "stoich" to, say, 14:1, and the computer will stop trying to pull as much fuel out?

    Or could I change the O2 Voltage Thresholds to higher switching points?

    Just trying to wrap my head around all this.

    Thank you all so much for your help!
    nope, closed loop is only capable of targeting what it percieves to be stoich, thats just how a narrow band trim system works. altering o2 voltage targets might get you +/- 0.1 afr or something

  2. #17
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    Just looking at temperature multipliers. These don't really make sense to me.

    IAT-ECT-Multipliers.JPG

    On one hand, the coolant multiplier at 108°C should be giving me 3% -more- BPW. On the other hand, the IAT at 38 & 50°C (what I'm currently seeing) isn't changing the BPW at all yet. Still, closed loop should still be trying to maintain Stoich, right?

    I -do- recall the stock 305 ran really strong for the first 3-5 minutes of driving, and then as it warmed up it became less and less exciting to drive. I never tested or scanned it before the engine died, though.

  3. #18
    Super Moderator dave w's Avatar
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    Screen shot below showing $OD closed loop tuning AFR averages with WBO2 data logs.

    BLM averages below 128 indicate rich / BLM averages above 128 indicate lean. AFR averages below 14.7 indicate rich / AFR averages above 14.7 indicate lean.

    Adjusting the $OD VE Tables rich or lean using WBO2 data, will have the same corresponding result (lower or higher AFR averages). Seemingly, adjusting $OD VE Table rich or lean will have the same corresponding results (lower or higher BLM averages).

    I don't know if other definitions (like $4D) will have the same corresponding closed loop results with VE Table adjustments like $OD?

    Some thoughts of some $OD WBO2 tuning I did:

    "it's so cool and fun to drive the Blazer now. I like how smooth it runs. No hiccups, no stumbles, no knocking, runs great cold, hot, uphill, downhill, doesn't matter what I do to the pedal it just smoothly handles the inputs. I like how the torque converter locks up. I like how you tuned it to run more in the torque range. Shifts are right where they should be for this motor. There's nothing more I can ask for in a tune. I am so pleased to have stumbled across you. I would never be able to learn how to tune as you do. Thanks very much again for your service."

    WBO2 - The best tuning tool ever!

    dave w
    Attached Images Attached Images

  4. #19
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    Humble pie.

    I max'd the Open Loop temperature, and set min and max BLM to 128, and went for a drive. OMG. Rich. Ok. So I will do a bunch of datalogging and mapping and get back to you all.

  5. #20
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    Mind you, it did throw a High-MAP, Rich-O2, and EST codes. I'll check those out first. Maybe make sure the chip was fully seated....

  6. #21
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    OK,

    With BLM restrained to 128, and Closed Loop turned off, I went and did some driving for about 40 minutes. Strangely, the ECU still went into open loop (gasp!). I could -see- "Open Loop" enabled on the TunerPro dashboard. Hmmm....

    Nevertheless, with the BLM restricted from going anywhere, it was just me, the VE table, and the O2 Voltage levels. It drove quite nice, with the NB and WB showing me just a few more slight rich and lean spots. I tweaked the VE based on the Average O2 Voltages per cell, then went for another drive with with BLMs now allowed to go as far as 122 (5%).

    Almost right away, the BLMs went 122 (my set minimum), ECU was pulling fuel, and I was getting into a lean surge. If, at 5% leaner, I'm getting into lean surge, I must have my VE table pretty close, no? Anyway - here is a screen shot showing the BLM Averages with BLM set to 122 minimum.

    18-07-21.jpg

    Makes me wonder, since it is STILL going into closed loop despite the Closed Loop Min Coolant Temp set to MAX, there has to be something else going on that I'm missing.

    While EGR temp was maxed to prevent it from operating (it is removed and blocked off), I went into both EGR Spark Advance and EGR Fuel Multiplier and set everything to 0 (it wasn't before) just in case it's being enabled despite my temp setting. I haven't tested this yet, but it's the tree I'm barking up right now.

  7. #22
    Super Moderator dave w's Avatar
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    Each ECM might work slightly differently. Sometimes it might be necessary to use a "belt & suspenders" approach to disabling a routine like "closed loop". For example, setting EGR on at 255 MPH should disable the EGR (belt only). Disabling EGR on at 255 MPH and disabling EGR on at 151 Celsius is "belt & suspenders" approach to disabling a routine.

    Usually changing the fewest possible parameters is a good strategy for disabling a routine. Maybe setting min/max BLM's at 128 is, or is not helping with disabling closed loop? Some definitions lock the BLM's at 128 when in open loop.

    Some definitions like $4D are not as thoroughly "Hacked" like one of the more popular definitions, for example $42. It's possible $4D has parameters that are still undefined? Maybe there is a $4D undefined parameter that would prevent "open loop"?

    dave w

  8. #23
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    Simulated narrowband sucks the o2 swings look very digital and can cause a lot of issues.you wouldn't be the first person who has used simulated narrowband and had perfect readings on the wideband but very low blms .it get a to the point that the swings of the o2 volts feel like a surge

  9. #24
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    I swapped the stock NBO2 back in, and the average voltages are confirming what I'm feeling, and still in line with what the WB simulated NB was doing. Still lean in a few spots, largely cruise around 30-40kPa. I've been fattening the VE table up a bit at a time, but I'm noticing that a 0.25 change only drops the O2 about 20mv, so I fattened the VE a full 1-2 points in the lean areas just now, and when my shoes cool down, I'll datalog some more.

    Shoes cool down? Yes. Immediately behind that red sheet metal is header. No insulation other than footwear:

    IMG_20180708_182016322_HDRs-672x504.jpg

    I still have BLM Min set at 128, and BLM Max set at 175, but despite reading lean, the ECU isn't fattening anything up. It's still saying that it's going open loop, assuming that it's not drunk. I -think- I have all the things to enable O/L on, I may have to check.

  10. #25
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    I did 7 drives today, tweaking the VE after each run. One thing I noticed is that the fuel pressure is not staying consistent. It's fluctuating quite a bit at idle (+/- maybe 3psi?), so who knows what's happening on the road. I was finding the fatter I made the VE the more lean surge I was getting. This has to be a mechanical issue.

    I have an external regulator on a shelf which I will use, then I'll alter the OEM regulator (currently made adjustable) and turn it into an accumulator to help cushion any fluctuations. I can't tune it if pressure is not consistent and stable.

    We'll see if that makes a difference.

  11. #26
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    Compare the o2 voltage thresholds table to the stock amyb_88_f-car bin copy it into your bin looks like that tables telling it what o2 volts to expect for 14.7 fueling. and the int delay base which will be how fast it decides to update off current o2 data and o2 proportional gains tables I'm pretty sure that's like the timing for how long it takes the o2 to get a reading down the header tubes and the int enable map and rpm are also different which could get you having closed loop changing while on decel or at the least down where the cam isn't alive yet

  12. #27
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    I initially used the amyb_88 5.0/5-speed bin, but there were some significant differences between that and the 5.0/Auto bin from my existing factory chip. Throttle Follower, in particular, drove the car kind of bizarre. My more pressing issue is a fuel pressure one; I need to resolve that one before I can go any further.

  13. #28
    Super Moderator dave w's Avatar
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    Quote Originally Posted by SkinnyG View Post
    I initially used the amyb_88 5.0/5-speed bin, but there were some significant differences between that and the 5.0/Auto bin from my existing factory chip. Throttle Follower, in particular, drove the car kind of bizarre. My more pressing issue is a fuel pressure one; I need to resolve that one before I can go any further.
    I'm wondering what type of fuel pressure gauge you are using? Liquid filled gauges can and will vary due to under hood temperatures.

    Interesting read: https://www.verociousmotorsports.com...-Filled-vs-Dry

    dave w

  14. #29
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    I'm using a liquid-filled gauge that came with the regulator.

    Previously I had just the gauge threaded into an aluminum T that I machined so I could read the supply pressure. The gauge fluctuated all over the place, and I could not find a consistent pressure. I had made the TBI regulator adjustable, but it wasn't holding consistently.

    Last night I took the spring out of the TBI regulator, removed the sealing-pintle-thingie from the diaphragm, reassembled it and plumbed the regulator. Now rock-solid pressure gauge!

    IMG_20180724_110326651s.jpg

    IMG_20180724_110312843s.jpg

    So, of course - take it out for a drive!

    Still going lean, even fattened up more! What the hell!

    And then a header gasket blew out (bolt came loose, I thought it was a burned valve - grrrrrr.).

    So now it's in my shop cooling down so I can get my hands in there. Hoping I can just tighten it up and it'll seal ok.

    I tell you, this car is kicking my butt.

    Until THAT is fixed, no new news.

  15. #30
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    Well, you guessed it. Tightening the bolts didn't work. So, I'll pick up a new header gasket tomorrow. Remflex this time, because grrrr.

    Sweet fuel pump pressure, though!

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