FF2Skip

VAFC-II installed and correctly displaying info.

The pressure signal input/output were connected to the Comptech ESM(I'm s/c'd). While we were able to adjust VTEC crossover and other features, the car ran like poop. We disconnected the pressure signal wires and the car had the performance back. Disconnecting these wires negates our ability to add/subtract fuel... right?

In this state, what are we doing wrong? The troubleshooting guide says to check if the sensor number is correct/check to see if fuel is set to an extremely rich level by the correction factor setting.

I'm searching for other threads, but I am in a hurry(isn't everyone?). The guy is staying late for me.

Thanks,
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AusS2000

When you say pressure signal do you mean MAP signal?

The V-AFC only effect tuning by changing the MAP signal and assuming that if the ECU sees more air it will add more fuel.

But the ECU doesn't like to see more air than ambient pressure and goes into a limp mode if it does. That's why Comptech supply the ESM. The ESM limits the maximum value of the MAP signal so the ECU doesn't freak out. Comptech then use a rising rate regulator to increase fuel with boost.

Depending how you connect the ESM and VAFC you are either capping a signal with the ESM, then modifying it with the VAFC, or modifying the signal, then capping it. Effectively you are using two conflictual tuning methods. This is the reason I've said in so many posts (just a search button away) that the VAFC is not suitable for FI tuning.

That said, some people have done things like capped the MAP signal even lower than the ESM/Vortech unit is set to and then used minor tweaks int he VAFC to tune, without going over the threshold. I do not recommend this.

I recommend an E-manage (it can add fuel by directly driving the injectors) ro go all out and buy an AEM EMS.

FF2Skip

Thanks, Aus. I agree that this is not the answer, however, it is only meant to be a very temporary state. AEM EMS will be purchased/installed in about two months. In the meantime, I only wish to make sure that I do not run lean.

As for which wire I mean, I am only going by the install directions. Yellow and white wires are pressure signal output/input.

tenblade2001

in other words... in 2 months, I will have a VAFCII in my car

AusS2000

Unfortunately you can't do this with a VAFC because the VAFC adds fuel by upping the MAP, and the MAP is already maxed.

You could try upping the fuel pressure, then lowering it with the VAFC but then keep in mind that the VAFC can really only control open loop tuning. When in closed loop the ECU will try to attain stoich by itself. The end result is that if up fuel pressure and pull fuel at most points along the curve, leaving it high where you need more fuel it will run fine open loop. But if you go up through the gears open loop, then back off the ECU will drop into closed loop and get all confused because it will initally see rich conditions but a low MAP signal.

Seriously, just leave the VAFC in the box and wait for the AEM.