yeah, it should go to about 16-20 degrees of advance once the circuit is tripped. i think that the MAP sensor has more to do with timing advance than the TPS does, because if i'm at like 30% throttle and manifold pressure goes to atmospheric, timing gets reduced to around 18 degrees, but i guess the ECU will retard timing to the "open loop" value if the TPS sensor goes to 3.8 volts or 100%.

the circuit needs 2 voltage refrences to know when to click the relay... there's the internal one (Vref) that's calibrated by a variable resistor, and the external one (Vin) that accepts a 0 to 5 volt input. this input can be hooked up to any type of MAP sensor that operates anywhere between 0 and 5 volts (or any other voltage output for that matter, hell, you could operate it manually with a button or something provided the voltage is higher than the cal resistor). for example, if i was using the stock MAP sensor i'd turn the key to ON and not start the car and turn the calibration resistor until i hear the relay click.

the circuit logic goes kind of like this:

IF (Vin >= Vref)
{
RELAY = 1;
}
ELSE
{
RELAY = 0;
}

if one was to use any other pressure sensor the calibration would go along the same route... the motorola pressure sensor that Corbin uses in a bunch of his projects can also be used, as long as everything is grounded at the same point. i think the motorola pressure sensor shows about 1.6 volts at atmospheric pressure.

Dino, that's a pretty good idea... building an electronic FCD into this circuit would certinly be doable, it would be nice to integrate everything into one box. however, i'd have to crack open that hunk of junk black box that i got with... um... and do some "research" if you catch my drift... something tells me that it's more than just a zenier diode...

anyways, i tested my creation last night in the lab here at work and it definately works now. in theory, it should work perfectly.

2016 WRX STi Limited (current)
2001 A4 1.8tqms (donated)
1991 GVR4 #1933 (sold)
old.dsmregistry.com/detail.php?carid=218 (dismantled)