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Thread: Fuel Trim Tuning (MAF) without a wideband

  1. #1
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    Fuel Trim Tuning (MAF) without a wideband

    Is it possible to do MAF tuning without a wideband O2 sensor? My LTFT's seem OK (between -5% and +5%), but at times, my STFT's seem a little far away from 0 and I'm not sure what to log/how to setup a histogram to tune the MAF table. I'm mainly concerned with part-throttle tuning as I rarely go WOT.

    Is this something that is even possible without a wideband? If so, what do I need to log/graph to do so?

    Or am I OK as long as my LTFT's are between -5% and +5% at all times?

    Thank you!

  2. #2
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    Actually, I found a nice tutorial that included the histograms for MAF tuning (since HPTuners comes default only with VE MAF tuning histograms). Sounds easy enough according to this article:

    http://www.silveradoss.com/forums/to...he-maf-sensor/

  3. #3
    Tuning Addict 5FDP's Avatar
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    STFT will always bounce around and be random, they change so fast and so often just based on the what your foot does and what the car thinks it needs to do to adjust fueling on the fly.

    LTFT with 5% of zero on a stock car sounds perfect to me, I wouldnt even be changing anything. If you could gain anything, it's not something you'd notice.
    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.

  4. #4
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    Ok, thanks. I didn't realize that it's "OK" for STFT's to be so far away from 0 at times. But LTFT's are just a long-term averages of STFTs, correct? If so and my LTFTs are between -5% and +5% then I guess I'm fine.

    I just get concerned when I see my STFT's at +34.4% when I'm coasting down a hill! :-) What I don't understand is they shoot up to 34.4% when the car goes into Open Loop when coasting - but I thought that fuel trims were disabled in Open Loop? Or am I completely confused?

    I'm not even looking at this stuff for performance reasons - just want to make sure I'm not risking engine damage becuase I'm super-lean when coasting or something like that... Obviously, I'm new to this! :-)

  5. #5
    Tuning Addict 5FDP's Avatar
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    GM would have addressed any issue like that before they even sold the vehicle to the public. Think about it, there is likely hundreds of thousands of your car on the road, all with the same-ish programming and nobody has had to worry it blowing up at random in stock foam to do fueling and trims.


    And when you are coasting, the motor doesnt need fuel at all. It turns itself into a air pump (even though they already are one), it will reduce fuel to a very minimal amount or it enters DFCO and shuts off timing and the injectors completely.
    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, so seeing +34.4% STFT's aren't an issue that I need to worry about then? I have disabled DFCO completely (didn't like the transitions, especially for the 4 second intervals when DFCO would be active).

    Is it "normal" for a car to enter Open Loop when coasting? I still don't understnad when/why a car enters Open Loop (except for PE)...

    Thanks for all of the help.