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I recently swapped FF380s into my NB2 with an MS3. Car has a rough start and AFR gauge says I'm idling at 22:1. I've changed my req-fuel. I read on FF's website that because the injectors flow differently than the stock injectors it will require tuning everywhere. I expected a change in tuning, but not for my car to run super lean.
To be safe I increased VE by 40% everywhere and it seemed to be alright.
Why is this? Don't they flow more? I asked a local tuner, and he said it was normal for FFs to require an extra 20% VE. Idle on stock injectors is around 30-40, but on the FFs its closer to 60-70.
I can't comment from personal experience, but I would expect that the relationship between injector pusle width and flow is non-linear for almost all classes of injectors. In the world I have some exposure to (pico- or nano-liter ink jetting, but both are piezo based so ¯\_(ツ)_/¯), generating a driving waveform for a specific volume is essentially voodoo-magic so I imagine any change of injector, Flow Force or otherwise, would require adjusting your controller. Perhaps someone who actually knows what they're talking about will chime in about their process for switching over to FF460s from stock.
I can't comment from personal experience, but I would expect that the relationship between injector pusle width and flow is non-linear for almost all classes of injectors. In the world I have some exposure to (pico- or nano-liter ink jetting, but both are piezo based so ¯\_(ツ)_/¯), generating a driving waveform for a specific volume is essentially voodoo-magic so I imagine any change of injector, Flow Force or otherwise, would require adjusting your controller. Perhaps someone who actually knows what they're talking about will chime in about their process for switching over to FF460s from stock.
I'm assuming that this is designed into the injector so that for idle fuel flow the injectors has a higher resolution, but for higher flows (where it might not as important), there's less waveform resolution.
I just wanted to double check that it is designed so, and that this phenomenon of lower flow at lower duty cycles is on purpose, and not a mechanical issue.
Whelp turns out it's definitely not a piezo in automotive injectors (there I go ***uming again). So not what I'm used to (piezo vs. lorrentz/voice coil), but as far as I see the injector is basically just a nozzle, an orifice, and a needle attached to a voice coil. There's nothing electronic happening inside of it that will adjust for what your ecu fueling behavior was before you put the injector the car. The geometry of the valve is different because you've changed it, you're also going to have to change the way your controller actuates it to achieve the same flow you had going into your cylinders as before. Unless you took the filters out of the new injectors or removed your fuel filter altogether, and if all 4 injectors are behaving the same, I wouldn't worry about anything mechanical and would just retune the controller.
Whelp turns out it's definitely not a piezo in automotive injectors (there I go ***uming again). So not what I'm used to (piezo vs. lorrentz/voice coil), but as far as I see the injector is basically just a nozzle, an orifice, and a needle attached to a voice coil. There's nothing electronic happening inside of it that will adjust for what your ecu fueling behavior was before you put the injector the car. The geometry of the valve is different because you've changed it, you're also going to have to change the way your controller actuates it to achieve the same flow you had going into your cylinders as before. Unless you took the filters out of the new injectors or removed your fuel filter altogether, and if all 4 injectors are behaving the same, I wouldn't worry about anything mechanical and would just retune the controller.
My concern was if the non-linear flow was an issue. It seems that it is typical for most injectors. The FF380s then have a different curve at the bottom end than the stock injectors.
02-11-2020, 05:36 PM
FF380 Flowing non-linearly
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