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Thread: What table moderates / affects Air fuel ratio as the coolant temperation rises?

  1. #1
    Tuner in Training
    Join Date
    Oct 2014
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    48

    What table moderates / affects Air fuel ratio as the coolant temperation rises?

    Quick question. My engine: turbo'd 5.3 . Tune is 3bar Speed density and is spot on regarding VE, starting, Full throttle, etc... BUT.... as the engine fully warms up, when I'm on the freeway and have the cruise control set to 75mph (for example) the wide band will begin to stay at 15.4 -15.6. Now when I first get on the freeway and the engine is not quite heat saturated, it'll be at 14.6 AFR. Its after the temps go from the middle of the first quarter mark to closer to the quarter mark (which is as hot as she ever gets), the fuel appears to lean out. What table in HPTuners is this that moderates fuel based on coolant temp? I'm still using HPTuners Pro version 3.6.26.

    Thanks,

    Dave

    '96 Z28 5.3 4L80E

    PT7675 93 oct. Best 1/8th mile: 6/4 @112mph, Best 1/4 MPH: 131 leaving at idle and transmission in drive

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
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    Rogers, MN
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    13,533
    Just sounds like your part throttle VE may need more work if it leans out once the engine is warmed up.

    If the open loop EQ ratio is commanding 1.00 (stoich) above 140-150 degrees, nothing should be telling it to command any leaner than that. If you have closed loop functioning your fuel trims would be working to keep the fueling around stoich as well. I also assume the IAT sensor is reading good and that's isn't throwing anything off.

    Could be as simple as adding 2-3% worth of the fuel to your cruising area's of the VE. I'd use the wideband to create an AFR error so you can log the error and copy/paste special the adjustments into the tune.
    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
    Tuner in Training
    Join Date
    Oct 2014
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    48
    Thanks for the response. I have had that wideband AFR PID for a couple of years and it's been great for all my VE tuning. I looked up and noticed I left out that it is an full time open loop speed density tune. I'll check the Open Loop EQ ratio.