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Thread: wot cammed afr issues

  1. #1
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    wot cammed afr issues

    I know that I probably missed a thread on something similar, but there are several issues occurring that don't make sense. Only conclusion is either I suck at tuning or the pcm is having an issue. Specs are 01 camaro ss, 65k, auto with 4l70e, 3.73 gears 8.8, all stock besides long tubes with dual axle dumps and a cam (222-233-113+3 lsa). Ive tuned another car, 99 trans am, same cam and mods runs perfect, this one not so much. I cannot get the afr correct under wot and trans will not shift consistently. Sometimes it goes to the commanded 6400 rpm shift other times it shifts at 5400 rpm. Afr is even richer than commanded. Can someone please attempt to see what ive done wrong or confirm there is another issue. Ive included two different tunes I tried amongst the mult others and hopefully the test runs I think I recorderic ve pat start test.hpteric test run.hpleric wot ve, maf 3.hpter vs pat 2.hpled.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Is this a cat-less setup?

    Where is the wideband installed and can you do a open air calibration on the sensor? You also forget to disable COT.

    The first log you posted has a much closer AFR to the commanded than the 2nd log. The fueling is richer than commanded but the injectors are not completely maxed.

    But then with the 2nd log you are running a leaner commanded AFR and actual AFR but the injectors are completely through the roof at 120-130% duty cycle.

    Something seems off with the sensor or fuel pressure if there is this much difference between the two logs.
    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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    Right the COT is not turned off but i didn't think that would be too much of an issue since there arent any rear o2s. And thats part of the problem is that the readings are all over the place and inconsistent. I even commanded 13 with pe on a run and still ended up at 12 afr at 4k+ rpm. any idea what sensor can cause this? I've also tried to respond 3 times now so hopefully this works.

  4. #4
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    Quote Originally Posted by 91camaro View Post
    Right the COT is not turned off but i didn't think that would be too much of an issue since there arent any rear o2s. And thats part of the problem is that the readings are all over the place and inconsistent. I even commanded 13 with pe on a run and still ended up at 12 afr at 4k+ rpm. any idea what sensor can cause this? I've also tried to respond 3 times now so hopefully this works.
    If COT isnt turned off i think it still runs the test.
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi

  5. #5
    Tuning Addict 5FDP's Avatar
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    There is no sensor that changes the AFR like that.

    If commanded is 13.0 but the wideband shows 12.0. Either the airflow model is that far off or you have a fuel pressure problem or wideband sensor problem.

    With fuel trims, closed loop, COT all disabled nothing else will change the fueling. There is a big spike in the MAF curve just over 10,000hz that shouldn't be there.
    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 turn off COT, and why turn off closed loop for a maf car? I will look at the spike in the maf. The wideband is good, I checked it with my other wideband in my personal car and got same reading. would fuel pressure be too high? bad regulator?

  7. #7
    Tuning Addict 5FDP's Avatar
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    You turn off fuel trims when tuning with a wideband, it's always been that way.

    Short term and long term trims can be turned on again along with closed loop when you aren't trying to gather data with your wideband. If trims are active when trying to get data for your wideband error, it will just skew all the fueling because the computer is correcting things for you.
    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.