[T3] Bad day at the (FI) office

[topnotch at nycap.rr.com]

the ECU really needs to see below 100 ohms (approx) to go full lean, (no warmup enrichment) otherwise the pressure  sensor wont track properly.
below 100 and the ECU essentially sees it as a short.  Many different sensors were used but their cold resistance was the difference, so it changed "how much choke" your engine had at a given cold temp.

adding a shunt resistor mimic's this, but adding a series resistor gets you over 100 ohms and richens up the hot mixture, this can mask the real problem and is not a good way to adjust hot mixture as then the hot mixture can wander somewhat and you dont want that.  These sensors were just for gross cold warmup adjustments.. they are not that accurate or linear.

Keith