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Thread: First drive after flashing always acts weird, anyone else experience this?

  1. #1
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    First drive after flashing always acts weird, anyone else experience this?

    After the first time this happened i thought it was my tuning and not the car and tried changing some more but now that it's happened repeatedly, i'm thinking its not me. Almost every time I flash my Camaro, I get crazy amounts of knock, like 8-15*, between 2 and 4k rpm in the .6-.88 airmass areas. But I drive it again later in the day, and not a spec of knock to be found with no changes to the tune. Is this a common thing or do I need to just start and stop my car a few times after flashing it to get the ecm to settle down?

  2. #2
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    My 2016 truck is weird right after a flash. Maintaining 55 mph for two minutes gets it back to acting right...

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    I'm talking about it doing this the morning after flashing it, the whole 30 minutes to work

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    What do your fuel trims look like in those areas?
    I've tuned a few things...

  5. #5
    Senior Tuner Frost's Avatar
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    KS starting over at initial levels following flash... set them manually.
    Steve Williams
    TunedbyFrost.com


  6. #6
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    I have seen this with my truck as well. It just seems like the knock system is relearning. after a few drive cycles, its back to normal. im glad someone else is seeing this because I was a little concerned. I always drive the truck easy after a reflash because of that knock.

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    Yeah, so today I made some minor adjustments to my flex fuel spark table before driving home from work. The car proceeded to do its typical 15* of knock above .7g airmass, with an added bonus of no CFCO or DFCO. 30 minutes straight of fueling. Get home, turn it off for literally 1 minute, go beat on it right after, not a peep of knock. So strange

  8. #8
    Killed the CAGS on my vette and the reverse lockout went bonkers for a bit. Glad I was paying attention. Thought it was weird enough to share here.
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  9. #9
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    Every time I flash my car I have to wait 24 hours before I can go WOT. These gen Vs are a mission...
    2019 C7 ZO6 M7.

  10. #10
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    Makes me wonder how guys can street and dyno tune at all, if every time they make adjustments, they have to simulate or go drive on the highway for a few minutes or something to reset the ecm with the new flash. Sounds like a huge PITA

  11. #11
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    Quote Originally Posted by ShaneB View Post
    Makes me wonder how guys can street and dyno tune at all, if every time they make adjustments, they have to simulate or go drive on the highway for a few minutes or something to reset the ecm with the new flash. Sounds like a huge PITA
    I ask myself the same question. I make a change, flash it, drive it for 10 minutes at first shut it off then go about my day putting the car through a few key cycles. Park it for the night then the next morning after the cold start is when I can go WOT and get my actual to match commanded. Anything before that the driver side bank won't match the passenger at WOT. Normal driving it's perfectly fine 0/-1 LTFTs.
    2019 C7 ZO6 M7.

  12. #12
    I may sometime notice just a little bit of KR on my first pull after a reflash. One time out of 10.
    I don't have to wait 24h or drive 30 min. This is weird what happens to you guys. And my knock sensors are left at stock sensibility...

  13. #13
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    Quote Originally Posted by Sachs View Post
    I may sometime notice just a little bit of KR on my first pull after a reflash. One time out of 10.
    I don't have to wait 24h or drive 30 min. This is weird what happens to you guys. And my knock sensors are left at stock sensibility...
    no need to rub it in that you hit the ecm lotto or something lol

  14. #14
    Senior Tuner Frost's Avatar
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    Quote Originally Posted by ShaneB View Post
    Makes me wonder how guys can street and dyno tune at all, if every time they make adjustments, they have to simulate or go drive on the highway for a few minutes or something to reset the ecm with the new flash. Sounds like a huge PITA

    I answered that just a few posts up... I tune knock sensors on the dyno along with fuel and spark. When you've done enough, it's like anything (spark for example) and you know where the platform will want to begin. You cannot tune them riding around looking at "KR"; you have to be able to KNOW what is real.
    Steve Williams
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  15. #15
    Advanced Tuner mbray01's Avatar
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    Quote Originally Posted by ShaneB View Post
    Makes me wonder how guys can street and dyno tune at all, if every time they make adjustments, they have to simulate or go drive on the highway for a few minutes or something to reset the ecm with the new flash. Sounds like a huge PITA
    when properly calibrated, an ecm shouldnt need any type of "reset" outside of whats done within the software.

    the purpose of a proper calibration is tell the ecm what it needs to know, so it doesnt have to "learn" anything before it acts right. in the past there were a few issues(injector tip temp) that created artificially rich conditions until a certain counter finished, or a wide open throttle blast. but those are non issues, when you address them before you even start
    Michael Bray
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    Quote Originally Posted by Frost View Post
    I answered that just a few posts up... I tune knock sensors on the dyno along with fuel and spark. When you've done enough, it's like anything (spark for example) and you know where the platform will want to begin. You cannot tune them riding around looking at "KR"; you have to be able to KNOW what is real.
    I'm not driving around trying to tune off of when it knocks. I haven't touched timing in a while, currently just dialing in the MAF curve. And I know its not real knock for several reasons, mainly because its still factory timing, with e85, and it'll retard 15* at light load one drive, and not at all anywhere the next drive. What do you mean by setting them manually? I can't find a special function or anything to command a certain threshold for the ks.

  17. #17
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    Quote Originally Posted by mbray01 View Post
    when properly calibrated, an ecm shouldnt need any type of "reset" outside of whats done within the software.

    the purpose of a proper calibration is tell the ecm what it needs to know, so it doesnt have to "learn" anything before it acts right. in the past there were a few issues(injector tip temp) that created artificially rich conditions until a certain counter finished, or a wide open throttle blast. but those are non issues, when you address them before you even start
    So what exactly is it that we need to address before hand to not have these issues?
    2019 C7 ZO6 M7.

  18. #18
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    Honeslty have never experienced like this this outside of trucks that would show "32*" on the outside temp display...even then the only issue was the ac not working right until that was sorted with a little time.

  19. #19
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    I know this used to drive me nuts when I first started trying to tune maf and vve tables. I?d make corrections after log and it would throw everything off the other direction. When you first reflash and Start vehicle, If you look at scanner I think you?ll see that your Intake Air temp will be pegged, which will screw with your fueling and timing via multipliers. I just start driving until the IAT drops back to normal before logging. Usually takes about 10 minutes or so. I?m still a Newbie but this info which I found somewhere on the forums helped me a lot.

  20. #20
    Senior Tuner Frost's Avatar
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    Quote Originally Posted by ShaneB View Post
    I'm not driving around trying to tune off of when it knocks. I haven't touched timing in a while, currently just dialing in the MAF curve. And I know its not real knock for several reasons, mainly because its still factory timing, with e85, and it'll retard 15* at light load one drive, and not at all anywhere the next drive. What do you mean by setting them manually? I can't find a special function or anything to command a certain threshold for the ks.
    It's under knock sensor level; Initial Level and Minimum Level. The EQ ratio multiplier is helpful as well. They vary based on vehicle.
    Steve Williams
    TunedbyFrost.com