I am in the process of wiring a Z18ET up, can anyone tell me what does the ECU use as an engine position signal, in other words what does it use to signal firing of the injectors and firing the ignition coils.

Isn't the dizzy on a Z18ET a points type? It doesn't take a position signal from the engine as such. Just the same as your old carbi engines.

Pick up for the injectors has me confused right now but as soon as i remember how it works i'll let you know.
It could be an RPM signal maybe
Very basic old ECUs thoes. Fuel only i believe.

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The dizzy is and electronic reluctor type. It has its own ignition module inside the dizzy cap that controls the coils. To give the ECU the rpm signal it wants you connect wire 18(on the harness) to the negative terminal of the coil, the one that controls the intake side spark plugs, not the exhaust stroke ones. I'll attach a diagram, I have afew more other diagrams too i will try to find.

Thanks guys. I'm still in the dark however, I already had the wire diagrams you posted and they ad to the confusion.
The diagrams have 2 wires coming from the distributor going to posts 56 and 57 of a connection plug and then i cant tell where they end up, this could mean that one of the wires goes to the ECU as a signal then the ECU fires the coil with wire 18, or the ECU uses wire 18 as a pickup to determine the RPM.
My car has a twin point mechanical distributor so that is not a real problem I can set the ignition up independent of the ECU, the real problem is with multi point fuel injection the ECU needs to determine the engine position to fire the injectors independently of each other at the right time, if it were throttle body injection it wouldn't matter.
The ECU needs a signal to tell it when to fire each injector, I haven't had the car long and I had hoped it would have either a cam angle sensor or a signal from the distributor to give it TDC # 1, I cant find either

Any suggestions.

it's batch fire (all at once) not sequential (individual)

Are you using an original z18 8 plug dizzy or something else?? the z18 dizzy controls retard and all that, if your using another setup you should account for the on boost situation.

also, the wires on the diagram you refer to coming from the distributor are part of the knock sensor and related wiring, which appears to be seperate to the ecu besides a shared earth and its not needed not make the car run. the number 18 wire is the one that needs a rpm signal I think you cound get this from the negative on the coil regardless what dizzy setup you have???

when i took my z18 wiring apart all the injectors were wired together to the signal for injector 2, and the positive wires all together to the drop down resistor. WTFF???!!!

The dizzy is 8 plug twin point

It has a build in module inside it, you can see it when you remove the cap, it has 2 trigger wires that control the firing of the 2 coils, one fires on the power stroke obviously and the other fires during the exhaust stroke to burn excess gasses and perhaps give a little push to the turbo lol. the other wires are to power the module i think, i never did finnish the z18 project...

once wired correctly you should be fine someone made a good list of what things are essential and non-essential to get the computer running, there should be some old topics on the subject.

Get your dizzy signal from the negative terminal of the primary coil. It's what keeps the ecu timing. The rest simply follows in a daisy chain effect.

Also the injector positive wires will be all wired together. For example. Battery>fuse>relay>dropping resisters>all injectors. The trigger wires are separate to the ecu and are neutral.

Any issues pm me. Done heaps of z18 wiring crap. Got a heap of spares too. Even a rebuilt electronic z18 dizzy I rebuilt in the body of a z24 napz dizzy. That way caps are cheap and readily available. Happy to lend out some parts for diagnostics.

Hey San, do you still have that decomp plate for the z motors?

Still working on my z22/224 turbo project. Just aquired a microtech digi 1+ fuel computer, was planning to go carby turbo actually but it was cheap.

How adaptable would an original z18 dizzy be to this sort of setup, in terms of advance and retard, will i have to run low boost, or modifiy the mechanisms?

Thanks

Whoa man blast from the past that decomp plate. I still have it, but forgot i did up until you mentioned it haha.

Essentially you would be able to run the z18et dizzy on the z24, so long as either you modify the z24 dizzy pedestal to accommodate the z18 dizzy, mainly the adjustment lock down bolt arrangement. Or use a z18 pedestal. It will bolt onto the timing cover the same. If youre z24 has the napz head on it, the wiring for the coils is the same. If its the aussie z24, you'll need to daisy chain another coil, but thats easy stuff.

Regarding the advance and retard control. Unfortunately that arrangement is all apart of the wizardry within the stock ecu and loom+components. The MT digi 1 ecu is pretty primitive. Im using the MT-4 fuel only setup and BB s2 electronic dizzy on mine with 9psi and it works, but with an ungraphed dizzy it goes a little silly when youre on the pedal and off then on again, occasionally you hear it hurting. Hence why ive bought a ms3+ms3x ecu. Allows for fuel and timing alterations.

If you were to run the stock z24 with the stock dizzy (as its graphed to suit that engine), put on the efi and turbo gear, run low intercooled (not super required for low boost), boost with a little water injection, the mt digi flowing enough juice, you shouldnt have too many issues. The z24 + boost pulls much more then the z18 does so you'll be using the torque more then the rev. Get a turbo that comes on early and go with it....thats if youre to a budget.

Heaps of ways to play around with it all if you wanted. Even twin head gaskets work. A bit ghetto though.

I have noticed there a 4 and 8 plug heads, and also square and round intake ports, the round ones have injector cutouts.

I have an 8 plug carby z24 in my pathfinder which i might leave alone, but I have just scored a z22 motor and manual gearbox for the pricey sum of 100 bucks(thanks ebay!). out of a 720 i'm guessing, they usually have an l18 or a z22. Cant see what ports it has from the photos and i havent picked it up yet. its missing the manifolds too so i dont know, i think its 4 plug. The same seller also has a rebuilt "z22" head which has the EFI intake ports but only 4 plugs. I have a z18 head at home which looks the same except 8 plug. The z24 square ports look bigger, i wonder if the carby manifold flows better than my z18 manifold...

Anyways i seem to have some options. but basically turbo this z22 maybe put bigger pistons in and make it 2.3

Fancy selling me that decomp plate?? I would LOVE some rediculously low compression

The digi1+ is better than the digi1, but yes simple. what gets me is it has no o2 sensor to adjust itself no closed loop, it only uses air temp, water temp, TPS, and a built in MAP sensor. The + model has about two times more tuning options in the software though, and i can throw away my AFM

Ill have to dig the decomp plate out of storage and see what condition its in. Hopefully the open air hasnt gotten to it. Shouldnt have. Might, pending my thoughts, be putting all my z18et gear up for sale too soon. including the 720 with the rebuilt engine and other trickery ive done to it... stay tuned.

Send me a pm so i remember to get the box from storage. Got a busy weekend ahead of me.