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

  1. #1
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    BLMs say rich, but WBO2 and NBO2 and surging all say lean - what gives?

    8063 ECU, $4D

    350, ported 882 heads, 256/262 cam, Holley TBI, GM Injector pod, 18psi, headers, all in a Pontiac Firefly (CDN market Chevy Sprint)

    EGR deleted and disabled

    TCC disabled (TH350)

    AIR disabled

    DFCO currectly disabled

    Can anyone see anything in my settings that I'm missing?
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    Last edited by SkinnyG; 07-17-2018 at 07:55 AM.

  2. #2
    Super Moderator dave w's Avatar
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    I do not have experience tuning $4D using a WBO2.

    I've tuned several $OD, $OE, $31, & $E6 vehicles using a WBO2. It's not uncommon to see WBO2 averages and BLM average contradict each other. I favor the WBO2 data vs. the BLM data.

    I like that $OD, $OE, $31, & $E6 vehicles have near idle and off idle tables, it's like getting the best of both worlds, near idle table for a smooth idle and off idle tables for good drivability and performance.

    It might be a good plan to upgrade from $4D to one of the following; $OD, or $OE, or $31, or $E6?

    dave w

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    Would the quick-and-dirty-button just be map it according to the WBO2, and tighten the BLM range so it doesn't pull too much fuel out?

    I had a thought that maybe high IAT might want to take fuel out, but still - wouldn't still try to hit 14.7? Intake air is a tick warm, 45°C recently. Open filter because there is no room under the hood of this car.

  4. #4
    Super Moderator dave w's Avatar
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    Maybe Open Loop Only, "tuned" by WBO2 would be the quick-and-dirty-button?

    Usually setting minimum temperature for closed loop to 151 Celsius will keep the ECM in open loop.

    dave w

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    Post a log

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    Odd. I thought I attached one. Now attached.

    The $4D is a pretty spartan computer by comparison.
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  7. #7
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    980mv full throttle she's rich .the old ecus also lock timing at lower rpm while in aldl mode it could be real retarded .where are your narrowband and wideband sensors installed if you install them one behind the other inline too close together you will get weird readings

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    You -should- be rich at full throttle; the Wide Band says 12.6 AFR at full throttle, which is what you want. Even at idle and cruise the WB is around 14.7, but the ECU keeps pulling fuel. I set the BLM limit to 120, becase it would go 108 and run super lean.

    It -is- getting timing, I've checked.

    I am using an LC-1 sending WB to a gauge and its emulated NB to the ECU. This ECU won't let me feed a WB for datalogging. While I have read that folks have had issues with the emulated NB on the LC-1, this ECU was doing the same thing with the original NBO2 the engine came with, as well as a brand new one I bought. O2 is mounted at the collector.

    I do appreciate the input and help. :) I can't figure this one out.

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    Fuel Injected! dktool's Avatar
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    Quote Originally Posted by SkinnyG View Post
    Even at idle and cruise the WB is around 14.7, but the ECU keeps pulling fuel. I set the BLM limit to 120, becase it would go 108 and run super lean.
    This sounds similar to the way my 7060 / $D8 system operates, the original minimum BLM value is 84 and it will pull fuel sometimes all the way down close to the minimum and all the while the WB02 holds steady at 14.7
    It seems to be under 50 map that it occurs the most, I played with lowering the V.E. in the rpm / map ranges that are most obvious and it lessened it some, when I changed it enough to keep the min BLM around 110 it would show a very lean condition on the WB02
    When the P.E. comes in the WB hits exactly 12.0

    It was something that was more curious than anything else as my overall tune is running fantastic.
    I have watched the live data for hours at a time while doing long road trips, everything else looks great.

    With all the emphasis on BLM numbers in the hundreds of posts I have read I tried real hard to get that magic number range everyone talks about but have come to the conclusion that this 7060 may well be the black sheep that eaglemark once eluded to.
    I just ignore the BLM data and use the WB as my guide.
    Dean

  10. #10
    LT1 specialist steveo's Avatar
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    there's also the argument that if you're going to run closed loop, you are never going to achieve the wideband AFR, all you'd be doing is making the BLM system work harder and harder to achieve an erroneous goal, so tuning to the trims would make more sense.. even if the AFR isn't great, at least it's consistent.

    in other words i would tune to minimize trimming or abandon closed loop and tune OL with your wideband.

    as far as PE goes, either method would yeild a reasonably accurate base fueling shape upon which power enrichment can be tuned properly to the wideband target anyway

  11. #11
    Fuel Injected! dktool's Avatar
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    Quote Originally Posted by dktool View Post
    I just ignore the BLM data and use the WB as my guide.
    I misspoke here, I meant " use the WB as a reference" being just to monitor what the CL fueling is doing and under all conditions (except P.E.) it runs at 14.7 regardless of what the BLM number is.
    Is that odd ?

    It's when I tune the V.E. to achieve a higher BLM number that it swings so lean that the drive-ability is gone.
    Dean

  12. #12
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    Quote Originally Posted by steveo View Post
    ...so tuning to the trims would make more sense.. even if the AFR isn't great, at least it's consistent.

    in other words i would tune to minimize trimming or abandon closed loop and tune OL with your wideband.
    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!

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    I am not trying to be a smart ass but I don’t understand. Above there was a line in the post.

    Even at idle and cruise the WB is around 14.7, but the ECU keeps pulling fuel. I set the BLM limit to 120, becase it would go 108 and run super lean.

    Which is it, 14.7 or lean? It can’t be both. If the WB stays at 14.7 the ecm is doing what it has been ask no matter the blm say. It would only look like the ve table wasn’t very good.
    6395, BHDF, 7.4 BBC lightly modded now 6395 BMHM back to BHDF

  14. #14
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    Ah, yes, that is unclear. My bad.

    I can fatten the VE table until I get 14.7, but the BLMs see "rich" and pull fuel. If I set the VE to what the BLMs want (I lean out the VE), the BLMs still see rich and pull still more fuel to the point of surging and lean misfire. The engine just doesn't want to run where the BLMs want to take it. The ECU wants it leaner, but the engine isn't liking it. Idle, cruise, doesn't matter, the ECU wants leaner. When I look at O2 Averages in the History Table, the -average- voltage is already reading lean where the ECU want to pull still more fuel. The voltages are making sense to what the engine is doing - when it "feels" and "acts" lean, the O2 is telling me "it's lean" and the BLMs are saying "it's rich; pull fuel."

    I've limited how far the BLMs can go (120 instead of 108), which has (for the most part) kept me out of lean surging (usually 14.7 at that point), but the BLMS will go right down to 120 trying to pull more fuel.

    I'm having a thought that the ECU might be seeing a high IAT sensor and mathematically pulls fuel, despite the existing VE and O2 saying "we're good." Just a thought....

    Does that make more sense??

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    I guess I should clarify: this wasn't a "known good" setup to start with. The factory tune "worked" (more or less) with the unmolested LO3 305 V8, but I've put a very different engine in and I'm sorting it out and trying to make it work.

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