After some consideration of my options, I'm almost set on going with VEMS for engine management. Anything that's cheaper is far less intelligent, anything that's more intelligent is also more expensive.
The car is an '89 S13 200SX w/ a built CA18DET engine. 1809ccm, 4 cyl, turbocharged, intercooled, multipoint sequential FI, COP ignition.
Aligning VEMS with the engine:
MAIN INPUTS
Air metering
Original
MAF
VEMS
4bar MAP + IAT (already have both)
MAP will be mounted externally, close to the IM, shortest possible tubing
5V supply comes from the ECU
IAT is a BMW type, res./temp diagram TBC
Crank angle, cylinder pos.
Original
mounted on EX cam, disc has two concentric rings for two optical pickups with OC outputs
(pulled on up ECU side)
Outer ring has 360 slits
Inner ring has 4 windows w/ lengths in slits: 16, 12, 8, 4 (not in this order, TBC)
(I don't yet know which window corresponds to which cylinder)
VEMS
using the same CAS with the "nissan 360 degree secondary trigger" option
Engine coolant temperature
Original
NTC regular type, 2.5kOhms at 20*C, 300Ohms at 80*C
VEMS
using the same
Throttle position sensor/switches
Original
Idle switch, closed when pedal released
TPS ~1kOhms - ~9kOhms for fully released, fully pressed, respectively
VEMS
using the same
Knock sensor
Original
1 channel, piezo type, mounted between #2 and #3
VEMS
using the same
O2 sensor
Original
N/A, stock narrowband removed, Bosch 4.x installed (probably 4.2, TBC)
VEMS
using the Bosch 4.x WBO2
MAIN OUTPUTS
Ignition
Original
Individual coil on plug, ECU outputs logic 5V signals for each cyl.
5V signals go to power transistors mounted in engine bay, these drive the individual coils
VEMS
using the same, putting out 5V logic signals
Q: how difficult to convert the IGBTs afterwards, if needed? (not likely, but still)
Injection
Original
lowZ injectors with dropping resistors mount in engine bay
VEMS
need possibility to drive either highZ or lowZ-s injectors, so "active flyback" option required
Q: do low-Z injectors still need dropping resistors?
Idle Control
Original
no idea, probably the same as any other Japanese vehicle from the same era, 2pin terminal
VEMS
using the same
Fuel pump control
Original
high side switch, probably, TBC
VEMS
using the same
Q: any "modern" features, like 6V operation, PWM closed loop w/ fuel press. sensor?
Auxiliary outputs
water pump PWM control for SSR (future)
[NOT YET FINISHED]