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.
WORK IN PROGRESS
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)
- Second idea for power... just because I have everything lying around for this. Don't know about the catch/flyback diode across the coil, I'd have to open up the relay housing for that, and they're sealed up tight.
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
- I would suggest to replace it with something simpler - i.e just one PWM valve. The original system contains 4 separate items: 1) A mechanical valve that closes when the coolant heats up; 2) A mechanical screw for adjusting the base idle; 3) A PWM valve that only changes the revs about +-200 rpm when hot (too little to use just that); 4) A valve for extra air when A/C kicks in.
- Thanks for the info, didn't know the idle valve was too small, now I get why all that extra mess is there. I've planned to get rid of the on/off AAC (no A/C) and the mechanical air regulator, too.
- How about running both IAC and AAC off the same PWM signal? Would that work and have the capacity to regulate idle across the whole range? (I don't want to buy/build anything extra I don't necessarily need.)
- Or, is there a cheap, off-the-shelf or junkyard idle air valve from another make/model that would work in place of the mech. air regulator? I could install that in the parking lot.
- Seems like a BMW M43-M50-M52 idle valves would almost work, except one of the 2 air hose diameters are not the same, as the CA18 air regulator. Would have to stretch the silicone over it.
- Thanks for the info, didn't know the idle valve was too small, now I get why all that extra mess is there. I've planned to get rid of the on/off AAC (no A/C) and the mechanical air regulator, too.
- using the same
- 4 wire bipolar stepper (lowest consumption)
- or BMW style 3-wire 2-input PWM valve
- or 2 wire 1-input PWM valve (the simplest)
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 ?
- By ECT I meant Engine Coolant Temperature. :) It's just the lingo I'm used to.
- 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).
Questions round #2
- How difficult to add inputs later, oil pressure, EBP, VSS, etc. ?
- I need a WBO2 extension cable. Any special requirements for this? Get one from ebay, or build it myself?
- Does VEMS use free-air cali. or the built-in resistor?
- What is the current version of the genboard (2016 May)? (which schematic should I look at, if needed)
- IAT, MAP, TPS, CLT... ground? Can all be common? Is any one of the grounds preferred for a sensor ground?
- Injector flyback compatibility table, is this correct?
| 30V flyback | active flyback | |
| High-Z | Y | N |
| Low-Z+R | Y | N |
| Low-Z in PWM mode | N | Y |
- Tach. signal - Nissan RPM gauge needs a voltage level. Any DAC outputs, or should I just add a properly sized RC filter to a PWM output, e.g. EC36 pin 4?
- On second thought, it may be PWM, FSM is foggy about this. Maybe I'll try without the RC first. Is there a test-mode to play around with the RPM signal before the engine is running?
- On second thought, it may be PWM, FSM is foggy about this. Maybe I'll try without the RC first. Is there a test-mode to play around with the RPM signal before the engine is running?
- How complicated to convert to 6-cyl later?
| Switched 12Vs | B/W, 49, 59, 109 | all come from ECCS relay, connected inside the harness |
| Grounds | 50, 60 and 110, 20,07,108,116 | these go to body ground in 2 groups |
Wire assignments (that I already know):
| ECU pin | color | orig.func | location of remote end | VEMS pin | new function | comment |
| 1 | R/W | Ign.1 | d/c | EC36 pin 35 | TTL output req. | |
| 2 | R/Y | Ign.2 | d/c | EC36 pin 33 | TTL output req. | |
| 3 | R/G | Ign.3 | d/c | EC36 pin 34 | TTL output req. | |
| 11 | R/L | Ign.4 | d/c | EC36 pin 36 | TTL output req. | |
| 101 | W/B | Inj. 1 | d/c | EC36 pin 7 | ||
| 110 | Y/B | Inj. 2 | d/c | EC36 pin 19 | ||
| 103 | G/B | Inj. 3 | d/c | EC36 pin 8 | ||
| 112 | L/B | Inj. 4 | d/c | EC36 pin 20 | ||
| 41 | G/Y | CAS TDC strobes | d/c | EC36 pin 27 | primary trigger | |
| 51 | " | " | " | " | " | " |
| 42 | G/B | CAS degree pulse | d/c | EC36 pin 13 | secondary trigger | |
| 52 | " | " | " | " | " | " |
| 18 | B/P | fuel pump relay | d/c | EC36 pin 15 | low-side switched | |
| 54 | Y/W | Idle sw. - | TB left side | EC36 pin 28 | MAP 5V supply | |
| 27 | G/B | MAF signal | front of engine | EC18 pin 6 | MAP signal | |
| 26 | B | MAF ground | front of engine | TBD | MAP ground | was common with other B pins in Nissan ECU |
| 57 | Y | idle switch + | left side of throttle body | EC36 pin 2 | IAT | |
| 48 | LG/R | TPS supply | d/c | EC36 pin 29 | ||
| 38 | LG/B | TPS signal | d/c | EC36 pin 1 | ||
| 30 | B | ECT+TPS ground | at TB | EC39 pin 5 | sens. comm. GND | Q |
| 7 | Y/R | tach. signal | d/c | EC36 pin4 | voltage level or PWM? | |
| 106 | SB | idle control valve | d/c | EC36 pin 17 | idle control valve | picked Inj_H channel for this (PWM) |
| 23 | W | knock sensor | d/c | EC18 pin 1 | ||
| 28 | L/OR | ECT signal | d/c | EC36 pin 14 | ||
| 16 | R/B | ECCS relay | d/c | n/a | own switching circuit, see top of page | |
| 45 | B/R | Ign. switch | d/c | n/a | own switching circuit, see top of page |
Wires still needed for new functions
| Oil pressure. sensor | will add later | |
| EBP sensor | will add later | |
| Water temp. sensor | will add later | |
| Water pressure sensor | will add later | |
Wires freed up (no equivalent function on VEMS, or not YET assigned to a VEMS function):
| ECU pin | color | function | location of remote end | comment |
| 6 | G/Y | A/C relay | ? a harness around the exhaust side | low side switch |
| 17 | ? | Check Connector | ? inside | |
| 29 | W | Lambda sensor | ? | WBO2 will be using all its own wires |
| 32 | ? | Check Connector | ? inside | |
| 33 | ? | Check Connector | ? Inside | |
| 115 | L | lambda heater | ?O2 orig. location | |
| 43 | OR | starting signal | ? key, probably | |
| 44 | G/OR | neutral switch | ?probably merges into harness around firewall | |
| 46 | L/G | A/C switch | ? inside | (A/C switch + blower on) -> 0V |
| 47 | ? | Check Connector | ? Inside | |
| 53 | Y/G | VSS | from gauge cluster | |
| 56 | ? | A/T control unit | ? | could be missing |
| 58 | R | constant 12V | ? | |
| 111 | PU | PR control solenoid | next to ign. power transistors | low side switch |
| 115 | L | lambda heater | ?O2 orig. location |
[NOT YET FINISHED]