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Thread: losing my mind over injector pulse width

  1. #1
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    losing my mind over injector pulse width

    logged INJPW in MPSCAN on my 90 daytona 2.5 turbo with stock cal

    At ~5400rpm, ~14psi boost, WOT, INJPW is around 5ms...

    That comes out to 45% duty cycle doesnt it?? Shouldnt it be 85%????

    help help help


  2. #2
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    Re: losing my mind over injector pulse width

    No, actually.

    http://www.stealth316.com/2-calc-idc.htm

    5ms at 5400 rpm = 22.5% injector duty cycle.

    Are you using 160lbs injectors?

  3. #3
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    Re: losing my mind over injector pulse width

    Quote Originally Posted by tryingbe View Post
    No, actually.

    http://www.stealth316.com/2-calc-idc.htm

    5ms at 5400 rpm = 22.5% injector duty cycle.

    Are you using 160lbs injectors?
    rats apparently the INJPW variable isnt fully understood yet and I guess cant be used to determine actual injector pulse width

    the actual injectors I'm using shouldnt really matter since the cal cant tell at WOT

  4. #4
    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
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    Re: losing my mind over injector pulse width

    The SBEC is especially complicated because the PWM drivers for the injectors are housing in the interface chip. No one knows exactly what this chip is, or how to get into it. So, there may be some timer math going on in there that affects the PW; though, I don't think so. All of the cals back to the LM have the same sort of disconnect between what the PWM timer calculates the PW out to be, and what the PW really should be.
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  5. #5
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    Re: losing my mind over injector pulse width

    Quote Originally Posted by ShelGame View Post
    The SBEC is especially complicated because the PWM drivers for the injectors are housing in the interface chip. No one knows exactly what this chip is, or how to get into it. So, there may be some timer math going on in there that affects the PW; though, I don't think so. All of the cals back to the LM have the same sort of disconnect between what the PWM timer calculates the PW out to be, and what the PW really should be.
    I just did some measurements with a scope of injector pulse width and compared it to MPSCAN and an OTC2000. Looks like the OTC2000 somehow figures out the correct value. I would think that would mean we just need to figure out what its little equation is and/or what variables its reading from the ECU. Perhaps we could monitor its datastream?

    http://www.turbo-mopar.com/forums/sh...PSCAN-OTC2000!

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