95 rover v8 nas and E.D.I.S conversion help

[DaveEFI]

The MegaSquirt lot these days don't recommend EDIS. Mainly because it sends a one pulse per cylinder to the ECU, rather than the 36-1 from the trigger wheel which is higher resolution. And being so old, the bits are getting harder to find. But on a relatively low revving simple engine like the RV8, it does work OK. Of course programmed ignition only is pretty rare. Most go over to injection from a carb/dizzy setup, with fuel only being far more common than ignition only. Same, really, as the direction the makers went.

[GDCobra]

On the 4CU there is a 6K8 line resistor between coil and ECU. Remove that, and it triggers nicely from a 5V signal. Not sure about the 14 CU.

FWIW, the diodes circuit from EDIS coils didn't work too well with my SD1 rev-counter. Ended up using a pulse amplifying circuit.

I did try linking without the resistor but that didn't work either. I must admit I could have fooled myself as there is a junction in the Black/White wire which leads to the coil, each going to a 6k7 (or possibly resistor then feeding to a White/Blue wire (clever making them same colour!).
It is possible I got the wrong one. Did mean to go back and try again but as I needed the diode setup for the tachometer anyway I didn't go any further with it. May have another go at some point, I've kept the Tach wire in my loom.

Just for completeness. I traced the other White/Blue wire it went to another plug/socket on the EFi loom, effectively passing straight through and having no part to play in the EFi system, presume it went to the dashboard tacho in the original vehicle, my tacho takes a feed from the cars loom already under the bonnet so didn't need that.

On a factory loom, I'd expect the ECU feed and the rev counter feed both to go to the coil negative. With only the ECU feed having the series resistor. I'm surprised the low volts tach signal from MJ doesn't work with the resistor bypassed, as it does on the 4CU, which according to the diagrams I've seen uses the same value resistor as the 14CU. I'd give it a try again, making sure you have the correct tach inpit wire to the 14CU.

Bear in mind though that I'm not using MJ, which may make a difference.
On my loom both the tacho and ECU feed went through separate 6k7 resistors, all of this was taped inside the loom and my loom was new, never previously fitted to a car so I don't think it had been modified.
I was tempted to give this a try but as my loom is already assembled and working and needs the diode setup for the tachometer I don't really want to fix what isn't broken. I may be looking at this again in the near future though, if so I will try this.
When I did the original work over the Christmas holiday it was freezing so I was hurrying a bit which is my excuse for possibly getting this wrong.

I'm just looking into the workings of the 14CUX system again and one thing I'm trying to get my head around is what affect the spark signal has and whether the system actually needs a signal for each spark event to work.

[DaveEFI]

Ah - didn't realize the resistor was part of the loom. On the flapper it is a small black tube with a spade connector either end mounted close to the coil, so very easy to bypass.

If there are two resistors, it's possible one is for the rev-counter and it would also work from a 5v signal, with it bypassed.

[GDCobra]

Ah - didn't realize the resistor was part of the loom. On the flapper it is a small black tube with a spade connector either end mounted close to the coil, so very easy to bypass.

The Hotwire is probably only a variation on that, it is in the loom but it is in a branch on its own, just the 2 White/Blue wires and a Black (can't remember exactly where that went but it's not connected to anything now - Only left in the loom as a spare) the resistors are basically each a rectangular box with a male spade either side. and the whole lot was inside the loom sheath wrapped in a load of insulting tape just a few inches in.

If there are two resistors, it's possible one is for the rev-counter and it would also work from a 5v signal, with it bypassed.

Maybe but I'm not using a rev-counter from the native vehicle. I don't seem to do anything the easy way!
Mine is a third party item and I don't know much about it. Was purchased over 20 years ago when I built the kit and I didn't pay much attention.

As it happens the rev-counter did actually drive from the Nodiz Tach signal but it only registered half the actual engine speed (correct speed inticated on tachometers in both Nodiz software and Rovergauge. There is as setting in Nodiz for the tach pulses per engine rev' and I'm not convinced that setting was getting made. Before I go any further with the Tach output I want to put a scope on it to see exactly what output I'm getting, frequency and voltage.