H22toF20

Someone did that on a camed H22 with good results but be careful doing it though. A VAFC leans out the mixture by adjusting the MAP values. The more fuel you take out, the more timing you're adding at the same time.

s2000Junky

I don’t use a NEO, I use a vafc2, so I cant confirm, but my inclination is that the NEO can not successfully be relied on to add fuel to an S2000 ECU either. Just like the VAF1 and 2, the unit parameters are there, but the proper technology is not when working with our ECU. In my experience when you add fuel, the car just stubbles and falls on its face, the ECU doesn’t know what to do with what you are asking. Cutting fuel works flawlessly, and I have used this on my Supercharged set up for years reliably and effectively, along with a rising rate adjustable fuel pressure regulator. The very one I used in the car when N/A to add fuel to my f22. I'd say if you find a good deal on a NEO, give it a shot, it has a few added features over the Vafc2 such as more fuel correction points for finer tuning, but don't go in expecting it to give you fuel or you will be disappointed. Use it as a way to shape your fuel curve by cutting the excess fuel from the added fuel pressure, and lower vtec. If you ask anymore then this from the unit it wont work for you.

s2000Junky

I have never confirmed or denied that aspect myself using a scan tool. But regardless even at my power level, I have never found this to be a consideration or detriment. Obviously setting the fuel pressure to a reasonable level as to not need a shit load correction/cuts form the vafc is the best way to go. Most of my cuts on the vafc never needed to exceed -12. The corrections will go to -50.

jh4db536

Question, when reducing fuel with vafc 'the timing is reduced'. Are we saying the ignition timing is advancing or retarding? Does the ecu still compensate for knock in wot/open loop mode?

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JUSTINTHECOASTIE

I also have an adjustable fuel pressure reg with VAFCII, my advice if you get dyno tuned and let the tuner worry about it,ECU doesnt compensate for WOT

whiteflash

I'm confused, what does fuel have to do with timing? Although I suppose in perspective if you're leaning out the AFR without touching timing, than you're reducing the efficiency of the timing in your new equation. I guess in that respect it's reducing, but...

In that case, your realistic timing has been retarded; your ecu will compensate by advancing, and yes it adjusts in WOT.

I'd also like to add that I've found consistantly on modded F22's that 0~2.2k, ends up having timing thats about from 2-5 degrees to high, and on the highcam about 3 degrees too low. I'm at work and don't have any of my logs with me so that's a rough generalization to give a clue.

H22toF20

research cylinder pressure vs timing and you'll realize why altering the MAP signal like this would increase timing.

EDIT Now that I'm on my labtop, I'll get into more detail.

It's not that you're decreasing fuel, it's HOW you're decreasing fuel. You're decreasing fuel by intercepting the MAP signal, the VAFC changes the signal and the ECU does it's thing. So what does this have to do with timing?

The higher the MAP pressure, the more air that's making it's way into the combustion chamber. This causes a higher cylinder pressure. Due to higher pressure and heat during the compression stroke, the higher cylinder pressure causes the A/F mixture to mix more effectively; faster combustion(flame front). You counter all of this by first adding fuel to reach the target A/F and also by retarding timing to counter the increase in flame speed. A lower MAP pressure, does the exact opposite.

Our goal with the VAFC, is to decrease fuel(sense we can't add). The VAFC, intercepts the MAP signal and decreases it. You're basically telling the ECU that their's a lower MAP pressure. So what does it do? It removes the fuel and advances timing.

JUSTINTHECOASTIE

ECU DOES NOT COMPENSATE AT WOT if running VAFC correctly(settings should be applied while ECU's in open loop)
READ My link

With increasing your fuel pressure(becoming rich) and having VAFC to lean it out it should fix your problem and give you NA gains at WOT

H22toF20

Really? So why would the VAFC allow you to remove fuel during WOT by altering the MAP signal?

JUSTINTHECOASTIE

If compenstate means counteracting or counterbalancing, then THE ECU DOES NOT DO THAT AT WOT, it only tunes out narrow throttle we are talking about fuel, now timing is another thing