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Thread: Confused on B3605 open loop commanded fuel

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    Default Confused on B3605 open loop commanded fuel

    I am currently doing an AutoVE and I noticed I was picking up knock at part throttle. I felt the timing wasn't excessive and happen to look at my commanded fuel pid GM.AFR (commanded fuel) and it is stuck at 14.63 throughout the entirety of the log despite my B3605 open loop table looking like:
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    I have closed loop diabled via the temp table, so what would cause the GM.AFR pid to be stuck on 14.63 and not match my open loop commanded fuel table?

    PS...I had my PE set to 14.63 so I could just work on the part throttle stuff, but my understanding is that the PCM chooses the richer of the PE table and commanded fuel in open loop table.
    Last edited by ddnspider; July 2nd, 2013 at 01:18 PM.

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    Joe (Moderator) joecar's Avatar
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    Check that B4206 is disabled.

    For you're engine's safety, set B3618 to 12.6.

    Yes, PCM chooses richest of active tables... if PE enables in OL, then the two active tables are B3605 and B3618.

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    Quote Originally Posted by joecar View Post
    Check that B4206 is disabled.

    For you're engine's safety, set B3618 to 12.6.

    Yes, PCM chooses richest of active tables... if PE enables in OL, then the two active tables are B3605 and B3618.
    B3618 is set to 11.5 as this is a boosted setup. B4206 is disabled....I am wondering since I recently updated my Tune/Scan tool and V2 firmware if I need to revalidate my pids.

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    Default Confused on B3605 open loop commanded fuel

    Curious as well because I noticed GM.AFR never changes either, even during warmup when the stock tune commanded slightly rich according to the equivalent table in the base OS. Is there another PID we should be looking at?
    14 GMC Sierra
    5.3L CC SB 4x4
    Basic tuning....

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    Quote Originally Posted by Wheelz View Post
    Curious as well because I noticed GM.AFR never changes either, even during warmup when the stock tune commanded slightly rich according to the equivalent table in the base OS. Is there another PID we should be looking at?
    Thats why I'm struggling is because it DID change prior to me updating my V7.5 scan/tune and V2 firmware.....
    ls7 SD log2-next day.efi7-2-13 open loop SD.tun
    Take a look at my tune/log and you can see my commanded open loop a/f table should be 12.0 from 70kPa up but when its logged it just shows 14.63. I believe it's messing up my BEN factor when I try to update the VE table. In this latest log I also tried logging Equiv Ratio and it stays at 1 also.

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    Should I be using Calc.AFR instead since I am using the serial wideband? But that still doesnt seem right. I pulled an old log on another car I did the AutoVE on and the commanded AFR changed in the log according to the open loop commanded fuel table.

  7. #7
    Joe (Moderator) joecar's Avatar
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    If you're using serial wideband (and even if you're using analog), you should use the pids EXT.WO2LAM1, EXT.WO2EQR1, GM.EQIVRATIO...


    see post #1 of the Calc.VET and Calc.MAFT threads...
    the calc_pids.txt file contains CALC.WO2BEN which is calculated form WO2LAM1 and EQIVRATIO...
    (and the post also shows you how to do this if you only have analog wideband connection)


    try to avoid using GM.AFR (there are several reasons for this).

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    Joe (Moderator) joecar's Avatar
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    Do you have CL and LTFT disabled...?

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    Quote Originally Posted by joecar View Post
    Do you have CL and LTFT disabled...?
    I was going off the autoVE tutorial and other threads I've seen referenced gm.afr. My concern is that if gm.afr is a valid pid based off of commanded open loop fuel table and its stuck at 14.63, then something in how either the tune or scanner is setup is off. I posted the tune, can you help verify that it's in open loop? I believe it is and logged that ltft and stft were both zero.

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    Also, I am using EXT.W02AFR1 to log serial wideband air/fuel and CALC.BEN1 to log the correction factor. So my map is simply Ben factor versus rpm versus map. Can you take a quick look at my tune and tell me if I am missing something?

    Based on what I can tell from the logs, it is trying to shoot for 14.63 regardless of whats in the OLFA table.

    I did find this interesting post:

    http://forum.efilive.com/showthread....l=1#post127363

    Where Weatherman Shawn stated that in closed loop it always chooses PE over OLFA.....if I had my PE set to 14.63 and I somehow didnt get it into open loop then maybe that is my issue. But the tune sure as heck looks open loop to me.
    Last edited by ddnspider; July 3rd, 2013 at 08:10 AM.

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