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Thread: Just a thought

  1. #1
    Tuner
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    Just a thought

    If the fuel pumps are set to on 12v constant do you still have to set the pressure multipliers to 1. The regulator should take care of all that right.

  2. #2
    Advanced Tuner
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    Im guessing your talking about a return fuel system with a vac/boost referenced regulator and the fuel injector pressure modifiers... In that case YES you have to set them to 1, and this is required BECAUSE you now have mechanical control of the fuel system. Those modifiers are there to characterize fuel flow when there isnt a regulator keeping pressure drop across the injectors constant.

  3. #3
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    so any fuel pump cut out that is commanded by the ecu is no longer in affect then since it is ran from direct voltage.

  4. #4
    Advanced Tuner
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    Ummmm... The ECU should still be commanding the pump to turn on/off. But in the fuel tables, in MOST cases, if its a modifier based on rail pressure (measured or inferred) it gets set to all 1's.

    When you go to a return system with vac/boost regulated fuel pressure, then it has very little to do with the fact that the pump is run off direct voltage. The regulator controls the pressure, and as long as its vac port is plumbed to the manifold, then its job is to keep the differential pressure across the injector constant. So the fuel tables that modify injector output based on measured or inferred rail pressure CAN be set to ones. One exception to this, is if your car has a FUNCTIONING Fuel Rail Pressure Sensor, then you dont have to set the tables to 1's.

    <<EDIT>> Your posts are very vague, and I cannot tell if that is deliberate or not, but it forces me to give generalized responses. Which Im not a fan of doing. So if you need further help/explanation, it would be fantastic if you would at the very least tell us what you are working with. Best would be to post at least a tune.
    Last edited by PST; 08-25-2016 at 10:41 PM.