Announcement

Collapse
No announcement yet.

setting up fueling for E85

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • setting up fueling for E85

    been working on setting up one of my cars for E85 now and ran into a few hang up's. the major one was no matter what i did to get the 30-40% more fuel into the engine from the 93 pump gas map for the car i used as a base my load value was completely out of whack. using the injector constant at 3bar with it set to 1600cc because thats what my injectors are and using the dead time chart that was provided with my injectors when bought was not working at all. i decided to try and understand better how the injector control worked and honestly all this is in the M232 wiki that PRJ has provided for us. after looking all that over again the only logical thing to do was to not use my actual injector size in the constant or my actual dead time table. than i got curious about how the base injector multiplier in VEMS is calculated so i went and looked. as a test i made a scalar in tuner pro based on this that would show the injector constant value in MS instead of the actual injector size. i calculated the time in MS using the equation from the VEMS help menu than added 40% to that value and and loaded that BIN to my car and it worked perfectly! a little too much fuel actually but i could than pull back the VE_MULTIPLIER and VE_ADDEND to remove fuel from and lean out the AFR mixture because i was off the gauge below 10.0AFR and doing so put my load right around 18-19 with all the right fuel. i also had to bump around the injector dead time table a little bit as well to find the sweet spot but calculating the injector constant in MS definitely worked for me.

    Heres what you need to make a new constant thats in ms.
    HEX address = 0x8399
    equation = X*0.0500
    decimal places = 2

    The equation from VEMS is as follows.

    -Inj time MS = 6.49 * (D / N / I)
    D: engine displacement (cc) = 2226cc unless you have a stroker
    N: number of primary injectors = 5
    I: injector flowrate (cc/min) = whatever your injector size is in CC.

    -This formula applies to gasoline, this value needs to be increased to run with fuels that have lower air fuel ratios. Typically 30-40% higher with E85, and more than double with methanol.

    so in the case of my car the equation works like this.

    1.8058425 MS=6.49 * (2226 / 5 / 1600)

    Than i used the simple online calculator below to add 40% to 1.8058425 to get the end result of 2.5281795 MS.
    http://www.percentagecalculator.co/A...ercentage.html

    im sure if this keeps working out positively for me i will make a convinence function similar to the one PRJ made for the MAP sensor scalars and pressure offsets easy to cope with. do something like put your injector size into a scalar and it does the math to calculate the time in MS for the actual constant than a second constant that will take the value in MS in your injector constant and add X % to it if running anything else other than pump gas. hope this is useful to someone and PRJ has input on it.
    "The really good drivers got the bugs on the side windows." Walter Röhrl

  • #2
    also to give a little update i ran the car with this configuration and at 30psi boost pressure i have 175-180 load ,11.8-12.0 AFR and i have not exceeded 200 yet on my VE table on E85. this seems to be the most effective way to get things in check for me.
    "The really good drivers got the bugs on the side windows." Walter Röhrl

    Comment


    • #3
      Originally posted by vwnut8392 View Post
      also to give a little update i ran the car with this configuration and at 30psi boost pressure i have 175-180 load ,11.8-12.0 AFR and i have not exceeded 200 yet on my VE table on E85. this seems to be the most effective way to get things in check for me.
      This is the point where you should forget the AFR, finally. It really isn't a number of measure.

      Stoich AFR for regular fuel is 14.7. Stoich AFR for E85 is 9.76. Stoich AFR for Methanol is 6.46. AFR is AIR to FUEL ratio.

      If you're doing E85 calibrations with regular fuel AFR you're completely ignoring the units of measure.

      But... When you do all things with lambda-value, stoich is always 1 and you go lean or rich in same way, not depending on the fuel or mix you use. That also should make more sense with the fuel mapping when you calibrate against lambda-values, not against some AFR nonsense. Different fuels need different adjustments, for example with E85 you can run pretty lean on WOT compared to regular fuel. But you should always compare lambda-values, not AFR.

      If you want to measure values in AFR, or get a point where you're going, you can always do maths. Lambda * Stoich = AFR.

      Comment


      • #4
        Be careful - all O2 probes are measuring Lambda, always. AFR is only a value which is showing you according to the set fuel type (lambda 1 = AFR 14,7 or something different).
        Working with lambda is the same as working with bar - the normal way, no us guy will ever do cause yeah they don't want it easy :-D :-D

        Comment


        • #5
          I have never been able to understand why anyone would ever work with anything other than lambda
          Panthero Coupé quattro 20vt
          Indigo ABY coupé
          Imola B6 S4 Avant

          Comment

          Working...
          X