how can a vafc work?
 

if my motor is runing wot,i thought it was working of a closed loop,wich i thought meant that it was strictly reading the prog. on the ecu,therfore how can a vafc wich i thought just basicly lied to the sensors to rich or lean out the fuel curve,possibly give me more fuel when i am at wide open throtle?
sorry in advance if i am completly off track.

Re: how can a vafc work? (chrisdata)
 

The VAFC is intercepting and altering the MAP signal while at WOT in order to alter the fuel curve, so this is actually when it's most effective (as opposed to open-loop, where the ECU is attempting to adjust the A/F ratio with help from the primary O2 sensor. However, the point you raise is one of the main limitations of the V-AFC. If the MAP signal is already approaching its upper limit, the unit can no longer increase the signal (and thus trick the ECU into thinking the motor is taking-in more air, thereby increasing the amount of fuel being injected). Because of this, it is commonly necessary for tuners to increase the base fuel pressure via an adjustable FPR. This increases the overall amount of fuel being introduced at any given MAP value, and the tuner can then lean out the fuel curve where necessary by "decreasing" the MAP signal at various points on the curve.