Distributorless ignition using GEMS coils and Hotwire system

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stevieturbo
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by stevieturbo »

GDCobra wrote:
Mon Oct 26, 2020 12:45 pm
stevieturbo wrote:
Sun Oct 25, 2020 8:45 pm
And the Nodiz claims it can fire both inductive and IGBT type coils ? So it can fire 8 LS coils just wired in a waste spark style. Just means it will be neater than using a pair of 4 tower coils.
Could be handy to have that available. Means I could set up initially with my GEMS coils, if I want to have a play and look into LS coils I could do and then if I wanted to go further and fire individually (not wasted spark) then I could look at new ECU and sort out a cam position sensor.
I don't really see the Cam-PS as problem, I'm going to be chopping down an old dizzy to act as an oil pump drive, don't think would be too much of a problem doing in such a way that I can add a trigger to it. My understanding is that the Cam-PS is used in addition to Crank-PS and used to indicate phase so doesn't even need to be so accurate, the actual timing still coming from the crank.
All correct...but as most electronic ignition dizzys already have all the parts you need inside for a cam trigger....not chopping it down so much makes it even easier.
Most would just want you to shave off all but one of the trigger teeth inside it, and job's done really.

In reality though, for an application like this, firing them sequentially vs "wasted" will make zero difference whatsover.

With both the RV8 and LS, I ran mine as a "wasted" style for about 12 years, as I just never bothered setting up a cam sensor.


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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by DaveEFI »

Thing with using the existing trigger in your distributor to obtain the cam signal is making the finished thing look ok. Fine if you're happy with a dizzy with no plug leads etc.
What can look neater is to strip the dizzy down, discarding everything except the main shaft and body. Turn the base plate for the advance mechanism (connected to the main shaft) into a single tooth or notch. And fit a hall sensor to read that. Cut down the body, and fit a flat plate as a cover.
Last edited by DaveEFI on Tue Oct 27, 2020 3:19 pm, edited 2 times in total.
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

DaveEFI wrote:
Tue Oct 27, 2020 9:49 am
Thing with using the existing trigger in your distributor to obtain the cam signal is making the finished thing look ok. Fine if you're happy with a dizzy with no plug leads etc.
What can look neater is to strip the dizzy down, removing everything except the main shaft. Turn the base plate for the advance mechanism (connected to the main shaft) into a single tooth or notch. And fit a hall sensor to read that. Cut down the body, and fit a flat plate as a cover.
I agree, one of the main reasons for going to individual coils n the first place is to tidy things up so a backward move to leave a redundant distributor in there and definitely can be done better

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by stevieturbo »

And easiest way to do that, is with no cam trigger lol. It simply is not needed for what is intended.
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by DaveEFI »

stevieturbo wrote:
Tue Oct 27, 2020 6:54 pm
And easiest way to do that, is with no cam trigger lol. It simply is not needed for what is intended.
But you still need something to drive the oil pump. You can of course make a stumpy, but not a lot more work to make a cam sensor instead, and future proof things.
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

Well, I pulled the trigger on this yesterday, Nodiz on order. Hope to be fitting it for very the Christmas break and I’ll keep updated here.

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

Unit arrived this morning, decent delivery, bit earlier than I was expecting really this time of this year.

Hoping to get some work done on it this weekend, although I've got a job to do on the daily driver so this will have to take second place, would like to at least get communicating wtih my laptop and get the CPS wired up so I can see that it's still working.

Even included a packet of Haribo which will make me popular with my wee granddaughter next visit!

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

OK, a quick(ish) update.

I ordered the Nodiz Pro just before Christmas and luckily it get delivered before the holiday.
Got it 'talking' to my computer easily enough via Bluetooth and had a play around with some of the settings and the map, all very straightforward.

First thing I wanted to do was test it with the trigger wheel and CPS which I put on the car a few years ago during my failed Megasquirt install, crimped a plug onto the end of the sensor wire, connected the live and ground to Nodiz fired up the engine (still on the distributor sysetem) and even before I looked at the screen I could see it was working as the blue and green LEDs were flickering away. Checked the engine speed in the EZ-Tune and was reading as per the cars tacho and the tacho in Rover Gauge (which I also had connected up to the 14CUX Hotwire sysem. Good start.

I then decided to try getting the engine speed pulse to the 14 CUX, so I cabled the Tacho output to the lead from the Hotwire and tried the engine. No start. That's a shame, was hoping to prove each stage of this out before moving on to the next but looks like the only way forward now is to switch over the coils and set up a signal to the Hotwire at same time, problem is if it fails I don't know where the issue is.

I wired up the 4 coil outputs to a plug for my GEMS coil along with a power supply and took a feed from each coil to a diode, linked the opposite side of each diode together and attached to the Hotwire input. Powered everything up and spun the engine over. The engine didn't start but I could tell from the fact the fuel pump cut back in and the signals in Rover Gauge that I was getting a signal from the coils.

OK, the engine didn't start straight away but it did cough a bit, after a some tweaking around with the Base Offset for the trigger wheel (which I still don't completely understand) I did get the engine to run and with got the timing correct (more or less) but not running well. After going back to the instructions and reading over I spotted a piece which indicated the coil sequence may be wrong. Swithched over 2 coils and hey presto engine started and ran well.

So now I need to work out the mounting arrangements for all the harware, make good all the wiring an cable ends and it will all be good to go. Unfortunately I won't be able to road test until Spring time (hopefully lockdown will be over by then!) but at least now I have control of the spark not relying on springs and vacuum diaphragms.

That is the broad strokes of the project, there are a few more details to fill in but I'll wait until I have the install tidied up before I go into all that.

I'm satisfied I went this way rather than Megajolt, happy not to have the additional EDIS-8 component and not to have had to sort out the mounting of a set of coil-packs. Happy also to have removed all the downsides of the pre-historic distributor base system with all its compromised. I'm also hoping that by the time I've sold on my (decent quality) destibutor and ingnitor this will actually be quite a cheap upgrade.

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by DaveEFI »

Excellent progress. Is there not a spare output on Nodiz which can be configured to give the same signal as the diodes from coils? That idea is only usually needed to give a high voltage pulse to older tachometers. Dunno about later systems, but on the Flapper injection the engine tach signal is obtained via a resistor from the coil negative. Remove that resistor and it triggers from a low volt signal. I made an adaptor lead to check a 4CU ECU using a MegaSquirt JimStim. It triggers happily from that.

You'd normally check the actual spark timing using a timing light and scale on the pulley, etc. Adjust the offset so the true timing agrees with the software one. With wasted spark a simple basic timing light can be best - some 'smart' ones don't like wasted spark.
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

DaveEFI wrote:
Wed Jan 06, 2021 10:00 am
Excellent progress. Is there not a spare output on Nodiz which can be configured to give the same signal as the diodes from coils? That idea is only usually needed to give a high voltage pulse to older tachometers. Dunno about later systems, but on the Flapper injection the engine tach signal is obtained via a resistor from the coil negative. Remove that resistor and it triggers from a low volt signal. I made an adaptor lead to check a 4CU ECU using a MegaSquirt JimStim. It triggers happily from that.

Cheers Dave. Only problem with that is I don’t know what is meant by “older”. Talking to some snowflakes would lead you to think that was pre-2018, to me “older” means pre 1960!

What I do know is that it has up to now both Tachometer & 14CUX picked up a signal from the -ve terminal of the single coil.
What form of signal it gets from here I do not know. I’d love to put an oscilloscope onto this to find out but don’t have access to one.
From what I’ve heard discussed I’m assuming this is a “high” voltage “spike” however I don’t know what is meant by high.
What I originally tried was linking the Nodiz Tacho output (apparently a 12v square wave) to the 14CUX (Tacho not mission critical at this point) and the 14CUX was obviously not happy with this, fuel pump didn’t restart and no RPM signal shown in Rover Gauge.
I then tried linking to the opposite side of the resistor (assuming I’m now working with a lower voltage signal, 12v), this did not work either so I moved on to the diodes.
I since realised that there are 2 feeds taken from the single cable linked to the coil (don’t know where the second one goes, need to re-check my data) and when I removed the (6k7) resistor I may have linked to the “wrong” input.
I will be re-visiting this before I make up my “production” loom as I’d rather use this, simpler, signal.

Once I had the engine running I then turned my attention to the car’s Tacho. I tried linking this to the Nodiz Tacho output and it did work BUT was reading half true speed.
There is a setting in EZ-Tune for pulse/rev’, obviously for a v8 this needs to be 4. Unfortunately I could not commit this setting to the unit, I could also not check what the current setting is, the software doesn’t make this obvious. I’m assuming it was set to 2, the standard setting for 4 cylinder.
I’ve communicated this back to Supplier. Hopefully this can be sorted but not worth trying to use this signal until I’ve got the correct frequency.


DaveEFI wrote:
Wed Jan 06, 2021 10:00 am

You'd normally check the actual spark timing using a timing light and scale on the pulley, etc. Adjust the offset so the true timing agrees with the software one. With wasted spark a simple basic timing light can be best - some 'smart' ones don't like wasted spark.
That’s exactly what I have done, but could only do that once I got the engine to run.
The suggestion from Nodiz is to put the unit in a mode which sets timing to constant zero degree then crank the engine (with start inhibited), watch the timing mark and tweak the base offset to get the zero point on the pulley to align with the pointer.
I had a couple of issues here. Firstly, although simple, my timing light does not flash when cranking, only when running so no way of working as per instructions.
Second issue was that the value for this base offset did not work as I expected so the setting I started with did not allow the engine to start.
Thirdly, although I can see the BO setting in EZ-Tune I could not set it, comm’s issue again, so had to set using the buttons on the unit. What I did was keep shifting the value 10* until the engine ran (just) at which point I could correct it using the (now working) timing light.
Now my zero degrees is correct any angle output by Nodiz will also be correct.
Hope that makes sense!

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by DaveEFI »

I've never had a play with a 14CU.

On my scope, I've seen a flyback pulse of about 50v peak at the coil negative. With older cars - ie single coil and dizzy there were different ways of driving an electronic tach - some used no direct connection but induction. However 'ours' sounds like the common way - direct from the coil negative.

The 14CU tach input will have an attenuator of some sort to prevent the 50v pulse frying things. On the 4CU it seems to be that outboard resistor. Although the JimStim provides a 12v pulse - I've not tried with the more common 5v one.
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

DaveEFI wrote:
Wed Jan 06, 2021 5:09 pm
I've never had a play with a 14CU.

On my scope, I've seen a flyback pulse of about 50v peak at the coil negative. With older cars - ie single coil and dizzy there were different ways of driving an electronic tach - some used no direct connection but induction. However 'ours' sounds like the common way - direct from the coil negative.

The 14CU tach input will have an attenuator of some sort to prevent the 50v pulse frying things. On the 4CU it seems to be that outboard resistor. Although the JimStim provides a 12v pulse - I've not tried with the more common 5v one.
That's interesting. As I say I need to look at the wiring to the 14CUX, there is a resistor in the line 6k7 ohm (presumably to reduce that 50v pulse) if I recall correctly so I unplugged this to by pass, I remembered later that there are actually 2 of these (all taped up in the loom) so I may have got the wrong one. It may be that if I put the 12v output from the Nodiz to the correct input withouth the resistor it will work, obviously I need to get this at the correct frequence first.


Another 'strange' thing I found. I initially put a diode onto each coil negative, joined the outputs and linked this directly to the 14CUX and it worked no problem. This should be simlar to the original, single coil setup, I'm simply using the diodes to get a pulse from each coil and preventing any coil impacting on another with the diodes. This worked fine for the 14CUX but when I connected the car's tacho to this (as per the original) it didn't work.
The suggested circuit also has a Zenner diode on the output (cathode to cathode) so I added this in to see if that woudl improve anything, although I didn't see why it would, and both the 14CUX and the car's tacho worked.

Anyway before I construct my permanent setup I'm going to try and get the Nodiz tacho output working as I'd rather not have the diodes on the coil, I can see a number of ways that could go wrong.

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by DaveEFI »

On my SDI with EDIS, never did get the diode method to drive the tach properly. (I've seen several circuit variations) It stopped reading at about 3500 rpm. I used the fly back voltage simulator - a transistor driving a relay coil to produce the spike. Driven from a standard logic output on MS, so 5v. The circuit for that wasn't perfect either - it didn't read when first starting, then kicked in when revved, and fine afterwards. I changed the transistor for a Darlington pair and that works fine. But could be my tach is odd. :D
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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by GDCobra »

DaveEFI wrote:
Wed Jan 06, 2021 6:44 pm
On my SDI with EDIS, never did get the diode method to drive the tach properly. (I've seen several circuit variations) It stopped reading at about 3500 rpm. I used the fly back voltage simulator - a transistor driving a relay coil to produce the spike. Driven from a standard logic output on MS, so 5v. The circuit for that wasn't perfect either - it didn't read when first starting, then kicked in when revved, and fine afterwards. I changed the transistor for a Darlington pair and that works fine. But could be my tach is odd. :D
Aye, you mentioned that Darlington pair circuit earlier in this thread (I think) that is also a possibility. I will be investigating all posibilties of using the tacho output rather than triggering off coils as it sounds like less complexity which I think has always got to be more reliable.

I'm also looking at my options for mounting the unit. I've got 2 obvious choices either on the firewall or the inner NS wing area (where my 'old' coil is mounted. I prefer the firewall as will be a better environment for the Nodiz box, but wiring, particularly to CPS will be better up at the front.
I'm now toying with the idea of mounting the unit into a box so no concerns with environment, and even better than on firwall.

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Re: Distributorless ignition using GEMS coils and Hotwire system

Post by DaveEFI »

Can you fit it in the same place as the 14CU? At least then you'll know it is a suitable environment.
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