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Thread: Airflow mode and O2 switchpoints.

  1. #21
    Tuner in Training
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    any information about how to setup the mode vs airflow? What do these values do exactly?

  2. #22
    Tuning Addict WS6FirebirdTA00's Avatar
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    Mode vs airflow is just a look up. I changed mine to give better airflow mode range so I didn't start off in say airflow mode 6 or something. Just gives better adjustability.
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB

  3. #23
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    I have played with this, some. I have seen a truck
    raise its closed loop idle AFR by a point or so, from
    mid-13s (using stock truck 0.500 switchpoint) to
    mid-14s (using stock F-body 0.350 switchpoint).

    I put mine down to 0.250 and saw an immediate
    increase in MPG, which later seemed to "go away"
    (back to baseline) and give me some tip-in ping.
    This was in pursuit of a quasi-lean-cruise result.
    Backed off to 0.300 later and left it.

    Now using this to fight the headers' thermal insult
    is likely to not produce any consistency. The sensors
    are just jacked when cold and you can't say how
    much. With long tubes you really want a thermal
    solution - either more heater power (good luck
    finding that) or modifications like wraps / shields,
    standoffs, opening up the gas-slots in the thimble
    or whatever.

    When you are getting decent cross-counts and
    waveshape symmetry, then the switchpoint value
    becomes useful / meaningful.

  4. #24
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    o2 Sensor help

    First Question i have for a gen 4 is as follows.

    My o2 sensors switch the lambda wideband from 1.01 -.97

    (MAF / SD tuning aside) What settings do i modify to change the switch point so it floats from 1.02 - .98. (i.e move the centrepoint slightly leaner so it doesn't dip into rich a long before it flicks back)

    Is this achieved with
    1: the switch point mv values which are set to 450mv stock.
    2: By playing with the mode vs airflow settings.
    3: Adjusting the min rich/lean and max rich/lean.
    4: Any other settings?

    Second question

    If the 02 sensors are switching slowly. do i just increase the Closed Loop Proportional > Airflow mode. So the 02 Switches faster? And if so by what increments.

    Third Question


    I have a B2 oxgen sensor that is slightly slower or behind the B1. It also has a more rough and jaggered line than the B1 and seems lazy, floating at around 450mv at times. Can experienced eyes look at this and let me know if any of the 02's need replacing, An exhaust leak produces this behavior or if its perfectly normal. Added the log file.

    Many thanks in advance!
    Last edited by Jamz; 12-05-2012 at 10:48 PM.

  5. #25
    Tuning Addict WS6FirebirdTA00's Avatar
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    #1 - lower your switch points

    #2 - depends, may need to increase or decrease the proportional fueling

    #3 - post a log in CL
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB

  6. #26
    Senior Tuner
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    Changing prop fuel might change the response
    (switching density) or not - depends whether it
    is driven by the actual prop fuel dithering, or by
    the intrinsic slowness of a cold sensor.

    Now a hot happy motor doesn't even need prop
    fueling to get nice fast switching - which going
    back from long tubes to shorties, gave me right
    back, instantly. Excessive prop fueling can give
    you wider swings that bury the sensor and take
    longer to back out, and bury the other way.

    There's also something about transport delay,
    which is absolutely affected by tube length to
    the sensor, and stands a chance of bringing some
    unstable behavior. I don't feel like I understand
    this well, but trying to correct for exhaust lag
    and doing it badly, can't help. I'd think that a
    tape measure based scaling of the delay might
    be reasonable although larger tubes also flow
    slower in their own right, distance differences
    aside.

  7. #27
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    I do have longtube headers and I have attached a closed loop log file for you to take a look at WS6firebird

    I also noticed in closed loop it takes some time for the commanded AFR to get to 14.7 even if the engine is already warm.

    1: Which tables effect that AFR during startup.
    Last edited by Jamz; 12-08-2012 at 06:05 PM.

  8. #28
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    I made some prop fuel changes and are switching more often

    I have attached the log.

    1: Can you let me know if one of the sensors is faulty, exhaust leak or it is plain normal to act that way.

    If someone has a log file of a good stock l98 with 02 sensors that are switching properly i would appreciated it you could post it.

    Thanks
    Last edited by Jamz; 12-09-2012 at 05:58 AM.

  9. #29
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    ive noticed the gen 4 have slightly different settings and noticed that i have poor switching on idle after my LT headers.

    ive tried changing the prop fueling but doesn't seem to help. Any transport delay settings in the Gen4 like the gen 3's?

  10. #30
    Advanced Tuner
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    Your answer is in post #8 in gen 4 it does nothing
    1997 Trans Am WS6 - LS1 swap - TR224 - Pacesetter Longtubes - Yank SS3600
    - 3.42 Moser 12 bolt - Wilwood Brakes - HP Tuners tuned - P1SC-1 Procharger