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:
POWER
See FSM page EF&EC - 80 for wiring diagram.
(ECCS = ECU in Nissan CA18DET terminology)
- Original
- The ignitions switch goes into the ECU, there it activates a low-side switch, which operates the ECCS relay. The ECCS relay supplies the actual 12V power to the (rest of the) ECU.
| color | function | |
| ECU pin 16 | R/B | switches on/off the ECCS relay |
| ECU pins 49,59,109 | B/W | ECU power supply |
| ECU pin 45 | B/R | Ingition switch, ign. on: 12V |
- VEMS
- VEMS has no provisions for this mechanism, it just needs its switched 12V, the end. We need to add this simple switching circuit ourselves, like this. All that is needed really, is a switching transistor.
- This is a quick and easy way to adapt one system to the other. Probably not the best one, but certainly better than powering VEMS from the Ign.Switch signal directly.
- For now, I'll just solder this directly into the wiring, cover all leads in heatshrink, and then ducttape the whole thing. DIYFTW! :)
- (Maybe a capacitor for filtering Ign. switch bounce? Gate resistor if a FET is used? TBC).
- NPN (BC817 or similar with a 2k .. 2k7 base resistor) is usually better for such things. Less sensitive than FET (which can be killed more easily, and badly needs Rgs).
- Flyback is a good idea in any case (eg. 1n4007 diode across coil, with cathode on coil+. Some suitable diode is included in rescue kit)
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
- Wiring changes - MAF
- Cut off MAF at the pigtail, it's 3 wires (12V, GND, signal). Use these for the MAP sensor, which also takes 3 wires (5V, GND, signal).
- Wiring changes - IAT
- Need to look for a suitable wire that will be freed up, and goes to the throttle body area, where the IAT will be located.
- 1 or 2 wires? Ground wire could be spliced into the ECT/TPS ground B wire, which is right there. Only 1 additional wire needed then.
- Idle switch? 2 wires from ECU, and idle switch is not used in VEMS, but TBC.
- Need to look for a suitable wire that will be freed up, and goes to the throttle body area, where the IAT will be located.
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
- CHECKED no. of degree pulses for Window slits High/Low (H L H L H L H L) 16 74 12 78 8 82 4 86
- 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
- Wiring changes
- The TDC (inner ring) and the angle (outer ring) signals are both wired double into the ECU, on pins 41+51, and 42+52, respectively. Probably a good idea to solder these together, before crimping it into a connector.
- JDM swap guys and RHD M/T guys should check their wiring/colors on FSM page EF&EC - 82. It's a bit unclear, the TDC and angle signal has the same wire color (G/B). Label them before you cut.
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, except idle switch is not normally considered (although it can be connected to a free analog input of course). Mixing in idle switch (pulling to GND, but through 10..20k) into TPS signal (for a voltage "step") is superfluous and should not be justified, TPS has all the information without this anyway.
Knock sensor
- Original
- 1 channel, piezo type, mounted between #2 and #3, shielding grounded to ECU ground
- VEMS
- using the same
O2 sensor
- Original
- N/A, stock narrowband removed, Bosch 4.x installed
- TBC 4.2 or 4.9
- TBC for any special requirements for an extension cable, twisting, shielding, etc., or just simple wiring
- VEMS
- using the Bosch 4.x WBO2 directly
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
- Individual coil on plug, ECU outputs logic 5V signals for each cyl.
- VEMS
- using the same, putting out 5V logic signals
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, 12V PWM
- VEMS
- using the same
Fuel pump control
- Original
- low side switch
- VEMS
- using the same
- Q: any "modern" features, like 6V operation, PWM closed loop w/ fuel press. sensor?
Questions so far:
Flyback type: which one for lowZ, lowZ+R, HighZ?
- 30V for High-Z (or lowZ+R), or active flyback if low-Z inj planned (to have the option to run without series +R).
ETC: for 2wire ETC, where is the 2nd wire connected?
- Between the 2 "bridge" outputs, see [VT Help]
- this engine has mech throttle, right ?
Triggers:
- primary=HALL
- sectrig=HALL, in order comment "Nissan 360 pulse HALL" (so smaller C103 cap is fitted than for the standard normal low toothcount sectrig)
- also refer to this page in order comment and add some signal/hangouts/skype/webrtc access if possible (for some discount; normally discount is only granted after successful documented install, but anyone who is prepared to a certain degree, deserves all kind of help from others too: prefer IBAN/pay later option, so full amount is not paid).
[NOT YET FINISHED]