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Thread: 50% throttle and early boost but lean AFR

  1. #1
    Tuner in Training
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    Mar 2015
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    saskatoon SK
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    Thumbs up 50% throttle and early boost but lean AFR

    My WOT is good in the mid 11's and my idle, crusing and light to medium acceleration all in the 14.0-15.0 area but this becomes a problem when boost begins to build around 2500rpm and im still in closed loop. Doing a brake torque i see that around 41-46% TPS is when i begin to build boost so I set my OL TPS THRESH to engage OL at 40%. I also make sure the FUEL BASE table at above 2500rpm and 35% tps commands a minimum .87 lamba at that point. Upon Datalogging a test drive it seems my changes have not made a difference and even at 3000rpm and 70% TPS i am still in closed loop. I must be missing something simple but cannot figure it out.

    On a similar note I would also like to be able to command a leaner 1.05 or so for light cruising and idleing for fuel economy as it get my tune worked out. Is the only way to do this change stoich to a leaner amount (i dont like "tricking" and falsifying data if there is a proper way) or run in open loop all the time? FUEL BASE only affects open loop operation right?

    At 4:16 of the log is where i rolled into othe throttle (but not going WOT) in 3rd gear to spool the turbo hoping to see the AFR reading take a dip as i passed 2500rpm but they stayed at 14.3 while boost boost built up to 4psi with no additional fuel inrichment. Am i going about this wrong or why isn't it working?

    thanks
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    05 mustang GT with 3v 5.0 and a 2.3 whipple

  2. #2
    Advanced Tuner Witt's Avatar
    Join Date
    Aug 2006
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    Pittsburgh, PA
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    380
    Took a quick glance and noticed your Cylair Max Multiplier should be raised to 1.99 for a FI car. If that doesn't help try disabling cylair anticipation.

  3. #3
    Tuner in Training
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    Mar 2015
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    saskatoon SK
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    I actually just had it at 1.99 but just reduced it to just above my max load prior to this tune. It had no effect in this instance.
    05 mustang GT with 3v 5.0 and a 2.3 whipple

  4. #4
    I could be wrong but I think that Cylair Max multiplier is simply a threshold. It will only effect fueling if you actually exceed the limit it is calculating for. So, if you are under the limit, then raise it, nothing should change fueling wise. If you do happen to hit the limit then you will start to lean out due to the PCM not recognizing any more increase in airflow?

    Myabe someone with more knowledge on the matter will care to chime in. I've seen a few tunes where this was just maxxed out on all motor cars even. Not sure if that's how it should be done but I doubt it.
    AAHHHHH!!!!!!