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Thread: Fuel: Injection Timing - M157/M278

  1. #1

    Fuel: Injection Timing - M157/M278

    Is anyone playing with injection timing?

  2. #2
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    I assume you were you going to change opening delay? I eyeballed that but figured it's probably set to the ideal timing already. No doubt ideal for emissions, but I'd imagine also power by default, more or less?
    For emissions I'd imagine it would be as late as possible, so I guess if I were to tinker I'd advance it by plugging in bigger #'s under 15 MPa?
    Next question in my mind is, if changing the timing to net more power at 6k, what about lower rpm? If 10deg adv works at 6k, then at 2k it's 30, which seems excessive. Probably isn't a big deal but I guess only only one way to find out.
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909

  3. #3
    Quote Originally Posted by chevota View Post
    I assume you were you going to change opening delay? I eyeballed that but figured it's probably set to the ideal timing already. No doubt ideal for emissions, but I'd imagine also power by default, more or less?
    For emissions I'd imagine it would be as late as possible, so I guess if I were to tinker I'd advance it by plugging in bigger #'s under 15 MPa?
    Next question in my mind is, if changing the timing to net more power at 6k, what about lower rpm? If 10deg adv works at 6k, then at 2k it's 30, which seems excessive. Probably isn't a big deal but I guess only only one way to find out.
    Yes, opening delay.

    This is informative on DI timing (you have to sign up for their newsletter to unlock the video.. otherwise there's a transcript below it):

    https://www.hpacademy.com/previous-w...tor-di-timing/

  4. #4
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    I wonder how our oem inj timing is determined. Meaning is it set to open at the same time all the time, or does it adjust based on rpm, cam timing, ign timing, load, fuel psi, all the above?
    Is Inj timing based on the start of the inj cycle or the middle? I assume the start but I never know what to expect here.

    I was wondering about fuel psi as well. My oem psi is basically the same 2450 all the time, but apparently adjustable. I've often wondered what would happen if the psi were bumped with rpm. Say 2450 up to a certain rpm, like 3000, then increase psi steadily to peak rpm. I dunno, maybe peak at 3-3200psi? I also wonder what that does to the qty of fuel injected? Will it compensate for the extra psi or will it simply dump in more fuel and trims will have to compensate?

    The timing and psi are two things are on my list of things to tinker with, but my list is long and testing takes a lot of time so it's way back burner. Also, my power changes way too much each time I floor it so it's basically impossible to notice small changes. Gains would need to be drastic for me to notice so I'd have to adjust each direction until it falls on it's face, then pick the middle and cross my fingers that's good.

    If you want me to try a certain setting, maybe to compare to yours, let me know and I'll tell you if I notice anything.
    '16 E550 Coupe RWD - C207.373 / M278.922 / MED17.7.3 / 722.909