VAFCII

[b.a.d. s2000]

This is gonna sound stupid, but what does VAFC do? does it give you more power? or it allows you to change the air fuel mixture? what exactly does it do? and what is the benefit of having it?

[Hondatwin23]

adjusts vtec points, fuel adjustments

[{X}Echo419]

don't be silly get the Uberdata!

[IntegraXTR]

V-AFC II can adjust vtec engagement, air flow, and fuel. If tuned you can gain more power, can't give you an exact estimate because it depends on your application.

[Ludester]

VAFCII..... well this is the worse method of tuning. But... and its a slitely large but; if your doing just simple bolt ons it will be just fine. Like I/E/H etc..its fine. When you start messing with cams etc its not a good idea. It doesn't excactly change the vtec point because it only taps into sensors on the ecu. Then the ecu sort off chooses when the vtec should change over. Which won't be until enough oil pressure is built up in the seloniod. So even if you lower the vtec crossover point on the unit it won't exactly change over until it has enough oil pressure.

[Ludester]

I forgot to add that after awhile the obd2 ecu rectifies the tune from it and you eventually go back to stock. yeah worse method of tuning man.

[scttydb411]

vafc intercepts your vtec signal and map signal to fool your ecu.

since the vafc intercepts the signal your ecu won't see or engage vtec until the set point that the vafc sends the signal out to the ecu. like was stated above, if you set it too low it won't engage until enough speed and oil pressure has built up.

in terms of the air/fuel it intercepts the map signal and the ecu thinks it is at a higher or lower vacuum. your ecu fuel and timing maps are determined by the rpm and vac. by intercepting the map signal and fooling the ecu, it will shift you in these maps effectively giving you more or less fuel depending on which way you go + or -. now the problem with this is it also shifts you in the timing tables as well since they also are determined by rpm and vac. by doing this you are effectively shifting yourself in the timing tables as well.

it's ok for small adjustments, but when you start really shifting one way or another it's control is less controllable so to speak.

if you're looking for a real tuning option i would suggest a tuneable ecu system instead of a piggyback.

what kind of car do you have?

[b.a.d. s2000]

s2k.

[scttydb411]

i'd suggest aem if you really want a tuneable system.