Understanding MFD - Help!
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Joined: Jan 2011
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From: Puget Sound
Understanding MFD - Help!
I now have all my readings for M*** Fuel Desired with Torque Pro, but I have big nozzles and custom tunes, so I have to apply a new formula to the readings for it to mean anything to anybody.
At first, I thought mg/stroke might be the weight of the diesel applied, but my brief research implies it's a concentration of fuel in relationship to the air. This is where all my "cleverness" totally derailed. I have a boost fooler, so at least I have a max indicated boost to go along with my max MFD at WOT - but MFD is still an arbitrary number until I compensate for all the customization on "Stinky".
How about it - any math/tuning wizards lurking about?
At first, I thought mg/stroke might be the weight of the diesel applied, but my brief research implies it's a concentration of fuel in relationship to the air. This is where all my "cleverness" totally derailed. I have a boost fooler, so at least I have a max indicated boost to go along with my max MFD at WOT - but MFD is still an arbitrary number until I compensate for all the customization on "Stinky".
How about it - any math/tuning wizards lurking about?
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Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
Your MFD is based in part on your throttle input (in AD counts in the calibration). In the most simplistic way, you can look at it as the PCM's best guess as to how much fuel you are demanding based on the pedal position.
How much fuel is actually injected is determined by many other tables in the calibration, quite a few of them take in MFD as one of the factors. So if you look for example at the injection pulse width, it takes MFD (your right foot) and ICP to help determine the initial pulse width. From there other correcting tables will account for timing, boost, etc to finalize the output of your pulse width.
The MFD table in the calibration is mainly used by tuners to smooth out pedal response, especially with larger injectors. Typically some tuners will massage this table to keep from having too much of a jerky pedal, or from having a pedal that is basically demanding WOT at 3/4 pedal like you see on the VDHx calibrations (and a few others).
Basic rundown, but that's pretty much it in a nutshell. There's not too much to overthink on the MFD other than it most closely follows accelerator pedal input.
How much fuel is actually injected is determined by many other tables in the calibration, quite a few of them take in MFD as one of the factors. So if you look for example at the injection pulse width, it takes MFD (your right foot) and ICP to help determine the initial pulse width. From there other correcting tables will account for timing, boost, etc to finalize the output of your pulse width.
The MFD table in the calibration is mainly used by tuners to smooth out pedal response, especially with larger injectors. Typically some tuners will massage this table to keep from having too much of a jerky pedal, or from having a pedal that is basically demanding WOT at 3/4 pedal like you see on the VDHx calibrations (and a few others).
Basic rundown, but that's pretty much it in a nutshell. There's not too much to overthink on the MFD other than it most closely follows accelerator pedal input.
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Joined: Jan 2011
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From: Puget Sound
The part that I can't work out is the mg/stroke. I have readings from idle to WOT up a steep grade, but I want to convert it to something that makes sense to me. For example: My initial plan was to have a reading that showed 0 - 160 CCs/1000 strokes (I should have started with Volume Fuel Desired).
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