It's a problem that has stumped 4 local mechanics and myself.
Here's a few details, hopefully someone has a random answer that will work:

B18C1 with a C5 head, Del Sol body. Nothing is stock. Literally.
n/a 10:1 comp, full custom intake, 55psi to 310cc injectors, & a friggen migraine.

The fan never starts but coolant temp is always low - even after driving a good 20 min. Locked cam timing back to zero. Replaced TPS, MAP, O2, FIT, IACV, coolant & air temp sensors (all within the month), and radiator was flushed & bled. Sensor signals & vacuum pressures check out, ECU was recently chipped & flashed.

No replacements, tweaks or diagnostics have made any changes or found any causes that would explain why it refuses to engage fuel control. Additionally, it repeatedly fails emissions testing (not that it commonly sees a city street, but... well whatever)

Any suggestions you can provide are appreciated.