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Thread: supercharged e85 vette: lean spikes on throttle change, weird MAP, PICS

  1. #1

    supercharged e85 vette: lean spikes on throttle change, weird MAP, PICS

    im still dealing with this issue lean spikes when gear is changed on WOT, i increased trancient fuel min fuel milligrams to 0.047, but it doesnt help. Also my MAP reading is very weird, is that because of belt slip?( doubtful just changed the belt and its like guitar string now) boost leak? (checked all the connections from blower to throttle body)

    2018 mustang gt a10 with headers and e85

  2. #2
    Senior Tuner Frost's Avatar
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    It's wideband lag; it's not lean in gear, it's during the shift. Look at the beginning of the pull. Look at how the green AFR lags the white commanded. Look at the gap and then look to the gear change point and you can see it's the same thing.
    Steve Williams
    TunedbyFrost.com


  3. #3
    Advanced Tuner umrjmac's Avatar
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    good observation!

    I don't have an automatic and haven't really spent much time looking at the tuning wrapped around the auto tranny, so is the lean spike part of that configuration, or is it something like DFCO triggering because the TPS goes to ~0 during the shift?
    Kenne Bell Supercharged 2003 Corvette Z06

  4. #4
    Senior Tuner Frost's Avatar
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    look at the white hump in between gears; it's falling out of PE (which is normal) and commanded fueling changes.
    Steve Williams
    TunedbyFrost.com


  5. #5
    Advanced Tuner umrjmac's Avatar
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    Perfect, thanks
    Kenne Bell Supercharged 2003 Corvette Z06

  6. #6
    Tuner KFZ)^'s Avatar
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    I think you need to let me drive it and I'll tell you what's wrong.
    Ha ha, just wishing I could see those 100+ kPa readings on my MAP. That car must be fun to drive.
    2001 Corvette Z06

  7. #7
    just for curiosity, how much fuel pressure are you running? assuming you've gone returnless.....

    as for the boost fluctuation, definitely not pretty. are you running a standard bypass or the a&a turbosmart part? i'd typically expect boost to just fade away with belt slip, not usually that erratic all the way thru a run....

  8. #8
    Quote Originally Posted by tommytuner View Post
    just for curiosity, how much fuel pressure are you running? assuming you've gone returnless.....

    as for the boost fluctuation, definitely not pretty. are you running a standard bypass or the a&a turbosmart part? i'd typically expect boost to just fade away with belt slip, not usually that erratic all the way thru a run....
    my fuel pressure is boost referenced. You can see that in IDC it goes up and down. Im in process of upgrading my blow off (orginal A&A suplied i think its vortech race valve) to procharger race valve. Ill let you know the results
    2018 mustang gt a10 with headers and e85

  9. #9
    Quote Originally Posted by ttbestas View Post
    my fuel pressure is boost referenced. You can see that in IDC it goes up and down. Im in process of upgrading my blow off (orginal A&A suplied i think its vortech race valve) to procharger race valve. Ill let you know the results
    Definitely report back on the procharger valve please.
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  10. #10
    Quote Originally Posted by jetttstream View Post
    Definitely report back on the procharger valve please.
    no change, i will do leak down test to make sure my intake valves are not leaking..
    2018 mustang gt a10 with headers and e85