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Thread: Supercharged 4.6 3V E85 Fueling

  1. #1
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    Supercharged 4.6 3V E85 Fueling

    Hello,

    I've got a 2005 Ford Mustang 4.6 3V that's pretty well modified and I just got it dyno tuned locally on E85. In speaking with other individuals with similar modifications the car doesn't seem to be making as much power as it should. I know dyno numbers vary significantly at times and aren't the best at comparing between setups but I started looking over some data for anything that might look out of place anyway.

    I took a datalog today and here are some of my findings. Unfortunately, I do not have an MPVI2 yet so the data is in LiveLink through an SCT device.

    What looks odd to me is the pressure drop across the injectors (highlighted blue line) and the way that my lambda value (highlighted orange line) starts to rise towards the end of the pull.
    I have a Fore Innovations dual ti274 pump return style fuel system controlled with a hobs switch and ID1000 injectors.
    This pull was done in 3rd gear from 2000-7000rpm.

    pressure_drop.PNG
    lambda.PNG

    Lambda is being logged with an AEM X series gauge and appears to vary quite a bit when WOT. Not sure if this is expected behavior or not.
    Any insight on what should be expected is appreciated. I'm newer to the tuning side of things and still learning some of the basics.

  2. #2
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    you dont have a manifold reference line on the fuel pressure sensor so its reading the fuel pressure and not the injection pressure (delta pressure).

    The fuel pressure rising with boost is because you have a 1:1 regulator which is raising fuel pressure 1 lb for each psi of boost so the injection pressure stays constant.

    Thats perfectly normal.

    Make sure your deltap multipliers are null in your tune if you still have delta pressure corrections enabled otherwise it will throw off fueling.

  3. #3
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    I cannot speak about the tuning side but I can say that I have a reference line coming from the manifold going to the FRPS as well as the Fore fuel regulator. Both are exposed to boost. The fuel pressure seems to be dropping with boost if I am reading the graph correctly.

  4. #4
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    I assumed that spike was where you shut the throttle

    if you indeed were still in it then yeah

  5. #5
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    Yes the spike was just after letting off. In the past with a different tune fuel pressure stayed at a constant 48ish psi even under WOT throttle with 93 octane and the same amount of boost. Now with this new tune and E85 it seems much different. To my untrained eye it's almost as if the fuel system cannot keep up but again I'm not sure what's going on in the tune that could make the data read as such.

  6. #6
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    the pressure is rising with boost

    If you have a boost referenced line and not vac referenced line on the frps then you have some funky jazz going on

  7. #7
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    I have had a problem with too small injectors. A good indicator is the duty cycle of the injectors. It can show some problems in the fuel system.
    If I interpret the pictures right, the fuel pressure drops and lambda raises.
    Is the whole fuel system e85 resistant or is there a leak?

  8. #8
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    The whole system is set up for E85. It previously had 93 ran through it and did not have this fuel pressure dipping issue. I was spinning the engine to 6000rpm on 93 before but now this is with E85 and I'm going to 7000rpm. I know E85 uses more fuel and my tuner said the injector duty cycle is "maxed out" but I have not been able to get data on that yet. I'm assuming it's around 90%.

    I'm thinking the issue might be that the mechanical regulator is before the fuel rails and the rails dead head at the front of the engine after being filled from the rear. My tuner said that he saw the pressure dropping in the data log but that the mechanical gauge was reading consistent like it should. I'm thinking that the mechanical regulator cannot keep up with the fuel demand when the rails dead head at the end. The fuel rail with the pressure sensor is on the hose run furthest from the mechanical regulator which I think supports my thinking.

    I'm going to work on configuring the fuel system to have the mechanical regulator after the fuel rails but that's going to take a lot of changes to the current setup.

  9. #9
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    wow, 7000 is real high for sc....

    and yes, that maybe the problem. The system must deliver much more fuel. So you have to log the cycle to be sure.

    try and error....every System is different.