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Thread: Having trouble reading commanded afr

  1. #1
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    Having trouble reading commanded afr

    I have a 2016 silverado 3500hd that I am learning how to use hp tuners on, and I am having trouble under standing why when it goes into pe the commanded afr does not change as it does on all of the other vehicles that I have connected it to. I do not have a wide band yet but plan on getting one soon as we are planning to put a cam in this truck after I get the basics figured out. Could there be something wrong with the truck or am I to blame? Any help or ideas would be greatly appreciated.
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  2. #2
    Tuning Addict 5FDP's Avatar
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    The AFR does change though. I see it several times in the log where the commanded air fuel ratio drops down all the way to 12.17 afr. One of the time stamps looks like Time: 08:07.20.

    Remove that Air Fuel Ratio Commanded channel, that one is not correct. The Equivalence Ratio Commanded channel is working as it should.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    Ok. So will I be able to set up an error histogram and tune it off of that?

  4. #4
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    Also what wb do you recommend?

  5. #5
    Tuning Addict 5FDP's Avatar
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    Yeah, you can setup a wideband error against the commanded EQ ratio. You just have to do the tuning in the proper way depending on what you are going for.

    I use the AEM OBD2 wideband, it's plug and play with vehicles using can-bus.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  6. #6
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    Ok sounds good! This is all new to me and afr is the only thing I understood before playing with hp tuners, Im still a little unclear how to use the eq ratio for the wideband error though.

  7. #7
    Tuning Addict 5FDP's Avatar
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    EQ Ratio is the commanded AFR. That is the way GM uses it. If you look in the tune file for power enrichment, the table should be labeled EQ ratio.

    In the scanner you can pick to log the commanded AFR or the commanded EQ ratio (aka commanded Lambda). The scanner lets you pick which units of measure for that eq commanded channel too if you right click it. There probably is a commanded AFR sae channel that you can log if you wanted too.

    So now if you were logging the commanded AFR or commanded eq ratio as well as logging your wideband, there should be a pre-made channel in the scanner for AFR error or EQ Ratio (lambda) error.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.