Tutorial: Converting EA81 to EDIS

[Silverbullet]

Here it is at last For anyone thinking about converting their older gen Subaru to distributorless ignition or wondering how difficult it is, hopefully this thread will tell you all you need to know.

I'll start by saying the electronic distributorless ignition system (EDIS) is a system that uses a crank angle sensor, toothed trigger wheel and electronic control module to fire a modern style coil pack as wasted spark ignition.. There is also another aftermarket ECU which then attaches to this system which allows you to control the ignition advance/timing via laptop and easy to use graphical user interface. The benefits of this system are:

- Precision ignition timing that can be dialed in to perfection for your engine
- No moving parts than can wear out and introduce slop into the system
- Modern coil pack with two individual coils inside, can run bigger spark gaps without a problem
-No more old, worn out dizzy, crusty dizzy caps or worn out rotor arms, no more points to adjust

Call it bringing an old engine into the modern era just a little bit

The downsides are that the parts as far as I can see aren't readily available in Australia (mainly the Ford EDIS module that is required) due to the donor cars not being available in Aus. The parts are readily available over the internet and ebay, you may just be paying a little more and waiting longer.

Parts list:

- Ford EDIS module. Can be purchased from this website along with the sensor and coil pack.

- VR sensor. There is one in the kit linked above but I didn't like it, it's too long and difficult to mount nicely on an EA81. So I bought an Audi sensor off ebay such as this. It has 3 wires but only 2 are used for this EDIS conversion.

- Ford Fiesta coil pack (see link above)

- 36-1 toothed trigger wheel. This is available from the above link or ebay but they are expensive and not quite the right size for EA81 3 groove pulley IMO. I drew one up myself in autocad and got it laser cut, so PM me if you want one, cost is $20 plus post)

- Megajolt ECU. I bought mine here with soft rev limiter. Be sure to add a serial tuning cable to your order so you can plug it into a laptop.

- Ignition leads. This one I got stuck on because the Ford coil pack as above has different terminals to the old dizzy. There is a small pin in the center, which needs a matching female part on the ignition lead which extends past the rubber boot to reach down into the coil pack terminal. I bought the right terminals off ebay here and if you do the same you will also need an ignition lead crimping tool. You can buy these as dedicated tools but since I already had a ratcheting crimp tool with interchangeable jaws I was able to find some ignition lead crimping jaws. Make no mistake - making your own ignition leads is a PAIN IN THE A$$!!! If you can source leads that have this terminal already on them, or if there is a coil pack that has the same terminals on it as the old dizzy this would be a much better option.
- Twin core shielded cable. This is for the lead between the sensor and EDIS module, and also the EDIS module and Megajolt ECU. It has to be shielded and it is very important to connect the shields properly to avoid interference in the signals going to the ECU/EDIS module.

- You'll also need other cable for wiring everything up, a relay is nice for switching the whole circuit on and off with IGN. If you use the same sensor as I did you might like to get this plug also as it means you can just plug your newly made harness into the sensor. If the sensor ever fails or is broken it is then a simple task to unplug it and install a new sensor. If you get this plug you'll also need a proper crimping tool so best thing is to head down to Jaycar and get their ratcheting tool and some jaws for insulated and non insulated terminals.


Other links:

Megajolt installation guide - Read, read and re-read this guide until you have a good understanding of the system. Also helps to print out a few choice pages to follow while you are under the bonnet.

Megajolt configuration software. You will need this little program on the laptop to talk to the Megajolt ECU and program the ignition map.


I think that's about it for a parts list It looks daunting and/or complicated and maybe it is. It's really not that bad though, I slowly collected the bits over a month or two as I needed them. Now you've all got a list to easily follow but I had to track everything down piece by piece which was not fun This conversion isn't a weekend job or something you can quickly throw together and go wheelin' It's quite a major modification for the engine but I think the benefits make all the effort well worth it.

That's enough of that, time for some pics and tutorial

[Silverbullet]

Mechanical installation

This will cover all the bits to actually bolt the system to the car. This will be just how I did it, you can obviously adapt for you own situation.

This is where I put the Ford EDIS module; where the original coil pack used to be. A custom bracket was required. If you can't fabricate something like this, you could also potentially just bolt it to the firewall or some other flat spot in the engine bay.




The coil pack was the hardest one to get right, as I couldn't find any convenient flat space to put it around the engine that wouldn't make the ignition leads a mile long. Then it occurred to me - why not put it where the dizzy was? So that's what I did This needed a very custom fancy bracket to be made since the engine isn't exactly a flat space. Basically the platform is welded to the engine lifting hook on one side. Also there is a small angle piece below the platform which ties into the M6 bolt hole where the dizzy locking plate used to bolt up. The hole is for access to the bolt. I'll also need a plug made to plug up the old dizzy hole.

The rope was to mock up where the belts were going to be.



In this image you can see how I mounted the trigger wheel and VR sensor. I found it best to make the sensor bracket and finalize that first, then position the trigger wheel to suit. It is VERY IMPORTANT to get the missing tooth of the trigger wheel correct in relation to the sensor. Basically, the 9th tooth before the missing tooth needs to line up with the sensor when #1 cylinder is at TDC. An easy way to do this is count 9 teeth from the missing one, on the 9th tooth put a center pop mark for reference so there is no way of putting it one tooth out. Since I was welding my trigger wheel to the pulley there wasn't really going to be a second chance! I don't think there is any way you could bolt a trigger ring such as this to the pulley as the pulley material is just to thin. Any bolts going through the walls would hit the belts in no time.

[Silverbullet]

Here is a more detailed shot of my sensor bracket. It bolts to the A/C compressor bracket using existing holes. If you don't have A/C, you'll have to find another way to mount this. Mine isn't fully welded yet, this was in case I needed to change it.





I think that just about covers the mechanical installation part. The only other thing is the Megajolt module itself which has to be housed inside the cabin as it is not weatherproof. This part depends entirely on where you can fit it. Mine is bolted in the area behind where the A/C and heater controls used to be. Since I'm putting a tablet there and not a double din head unit I've got plenty of room behind there. As long as you can easily run the wires to it and a vacuum soupply for the MAP sensor inside the Megajolt.

Electrical

This is probably the part that will throw most people or seem the most daunting. Just take it one wire at a time though and you should be fine

Probably the hardest part is wiring up the EDIS module itself. Since these are all used modules they come with a pigtail of wires hanging off them which you have to solder to. I was really not happy with this but new plugs aren't really available or are horrifically expensive. So make sure you know how to solder and heatshrink for this. Label each individual wire coming off the plug following the guide so you don't make any mistakes. I made one error (explained below) since the wiring diagram was wrong and so ended up with one wire that was nearly not long enough to solder to. That was a bit stressful!

The main error in this image is circled in red below; it shows the sensor cable shields connected to pin 7 on the EDIS module and also connected directly to ground. This is WRONG!!! Do not connect the sensor shields directly to ground, only connect them to pin 7. Pin 7 is internally connected to ground inside the EDIS module, so by connecting the shields to pin 7 and ground there is a ground loop going on, which in the sensor circuits side of things is the worst possible thing that could happen. So first time round my ignition did not work, some research on the net told me the wiring diagram on the Megajolt website is wrong.



It says in the Megajolt guide to ground the Megajolt ECU and the EDIS module at the same point. So I ran a wire from the ground pin of the Megajolt to the outside of the car, and joined it to the ground wire for the EDIS module which was then bolted to the chassis/body. For 12v+ I added a relay with 2 x pin 87. The fused power comes through the relay then one pin 87 to the EDIS module and coil pack, the other 87 goes inside to the Megajolt.

Wiring up the coil pack is simple enough, 12v+ goes to the middle pin and then the 2 outside pins go to the EDIS module. make sure you get coil A and coil B the right way around. If you get the coil linked in the kit in the parts list you will get a new coil connector and terminals. This is a sealed type connector (very nice!) you will need a proper crimping tool to attach the terminals properly. Practice first because you only get 3 terminals with the plug For security I also added a tiny dab of solder to the exposed copper ends after they were crimped into the terminal for a really good electrical connection.

The sensor is pretty straightforward, if you use the Audi sensor as I did you want pins 2 and 3 inside the Audi connector. This cable needs to be shielded type as mentioned before and also the sensor is polarized. So if the engine doesn't start first time then try swapping the 2 sensor wires around. With the matching Audi plug linked in the parts list this is quite a simple task.

Below is how I arranged the ignition leads.



With the coil connector on the left this is the numbering, pretty straightforward

[Silverbullet]

The wiring at the Megajolt end can be much simpler, it really only needs 4 wires for operation; power, ground, PIP and SAW. The PIP and SAW wires need to be shielded as shown above, with the shield connected to the sensor shield and then pin 7 on the EDIS module under the bonnet



Here is a more detailed pinout for the ECU, it is possible to add auxiliary outputs from this. For example, you can wire in a coolant temp sensor to the ECU, and program it to trigger a relay when a certain temperature value is reached. I haven't played around with this much yet so I'll have to add more to this thread when I get around to it. The 16 pin plug that goes into the Megajolt is included when you buy the unit, again you will need a proper crimp tool to attach the wires and then push the terminals into the back of the plug where they click into place.



If you have a tach in your car, there are a few ways to wire it up to this system since the old coil no longer exists. The way the old tach works is by being connected to the old coil negative post. Every time the coil is grounded it creates a spark event in one of the cylinders, with the tach connected to coil ground it turns this pulsing into a needle movement through some diabolical mumbo jumbo inside the instrument cluster. Because it uses the negative impulses from the coil we can't use the tach output from the Megajolt since that is a positive pulsing signal (if you have an aftermarket tach that uses positive pulses you can use it)

Now because we essentially have 2 coils there are really 2 coil negative posts (the two outer wires at the new coil pack) If you were to connect the old tach to just one of the coil wires I'd be willing to bet the tach would indicate half engine RPM. The Megajolt installation guide mentions their wiz bang tach adapter board (which I bought) that has some diodes on it as pictured below. This didn't work for me either on the first engine fire up and I couldn't work out why. Some more thought on the subject has led me to thinking the tach adapter circuit below is wrong for our cars, the diodes should be the other way around. I'm yet to test this for myself so stay tuned.



***EDIT*** 4/7/16

Can confirm the above circuit with diodes does not work with the stock MY tacho. Neither did my idea of turning the diodes around in that circuit. Having done some more research on how the stock tacho works, it seems something a tad more complicated is required. See below:



I will try the above circuit with a gutted relay which should imitate the original ignition coil. That picture is for megasquirt ECU but the megjolt ECU also has a positive + tach signal pin which can be used to drive the transistor. Full explanation on page 2 of this thread since I don't want to clog up this post with super technical jargon


So if you've gotten this far in your installation you can attach some spark plugs and give it a crank. For the first try it is best to disconnect the Megajolt to see if the system works and the engine runs just on the EDIS module. The Ford module can run the engine at a fixed 10 degrees BTDC. If you're lucky it will fire right up, if not then try swapping the sensor wires around. If it still doesn't work then you have a wire the wrong way around somewhere or the trigger wheel isn't in the right place.

When you get it running, give yourself a pat on the back and rejoice that the hardest parts are behind you Next thing is to connect the Megajolt, make sure it has vacuum going to it and start making an ignition map. The map is going to be annoying because we are pretty much starting from scratch. I started by trying to copy the factory ignition timing curve from the FSM into the ignition table. But I soon found the graph in the book is woefully lacking in detail. I'm still working on this part myself, when I'm done I will post up the map I've made for others to use but it still wouldn't be perfect for your engine since I'm running twin carbs. The map has to be tailored to your car, best thing to do would be to get the car drive-able and get to a dyno which is what I'll be doing.

I hope that covers everything, I've been here for 90 minutes now typing this so my brain has turned to mush a little bit If I've forgotten anything I'll add it to the posts at a later date as well as any updates as my project progresses. If there's any questions fire away and I'll do my best to answer them. There is one other member on here (Subydoug) who has done an EDIS conversion to his MY wagon, but he is using the Megaaquirt system which also controls fuel injection.

Enjoy!

[steptoe]

see me to delete this place holder

[El_Freddo]

Awesome work SB! Neat write up too.

This makes me think I'll stick to reading factory MPFI and ecu wiring diagrams. That seems much easier to me! But then again I don't have a need for this system so I don't have the same drive for this.

Love your bracket work too mate!

Cheers

Bennie

[Proton mouse]

turns this pulsing into a needle movement through some diabolical mumbo jumbo inside the instrument cluster.

Haha I always wondered how they worked, now I know lol
Great write up Sam!!

[steptoe]

just been looking at my EA82 NA pulley on the kitchen table. There is no keyway so would need some attention to fit it with holes from a belt drive cog and spring roll pins to keep it in place, two off-set so only goes back on one way. Did you do anything to prevent the pulley from realignment problems in the future Sam?

[Silverbullet]

Awesome work SB! Neat write up too.

I don't have a need for this system so I don't have the same drive for this.

Thanks mate!
Does this just show how much I hate the EA81 dizzy?

Jonno, EA81 crank pulley has a keyway so no chance of misalignment

[El_Freddo]

Does this just show how much I hate the EA81 dizzy?

Yeah I guess. I solved my lifter tick in the EA82 with an EJ conversion So I know exactly what you mean

Cheers

Bennie

[Bantum]

Awesome write-up there Sam ...

If I ever consider doing this in the future, be sure to bookmark this for future reference ...

P.S. - Someone should make this a sticky as well ...

Ciao, Bantum ..

[Silverbullet]

Explanation of the OE ignition coil and tach

After some experimenting with the EDIS coil pack and stock tach I found it is not possible to drive the stock MY tacho with the coil pack. At least not with diodes anyway, I'll explain below but beware! technical jargon ahead, you don't have to read it mainly to get it out of my own head hehe

I was almost right in my explanation of how the ignition coil works, and how it drives the tacho. The way the ignition coil actually works is that it is always "on", as in it always has 12v going to it and is always grounded *in between spark firing events* which builds up a magnetic field in the primary winding of the ignition coil. A spark event is caused by the points (or ignition module) breaking the circuit for the coil (in this case the coils connection to ground) which causes the built up magnetic field to collapse. As this magnetic field collapses an extremely high voltage is produced in the secondary winding of the coil which is what fires the spark plug(s) The same things happens in an A/C transformer which is how you can turn low voltage A/C into high voltage A/C or vice-versa. The ignition coil is basically a transformer, but using DC constantly switched on and off.

In addition to the secondary voltage, a spike of high voltage is also sent down the negative side of the PRIMARY windings of the coil. If you have any understanding of how inductors work then this will make sense. And this is where the tacho comes in; this spike of high voltage is sent down the negative side of the coil which the tach is connected to. The circuitry in the tach takes this spike of high voltage for each spark event and turns it into a needle movement with a simple circuit and IC chip inside the cluster. My theory is that as soon as you put a diode in this line to the tacho, that high voltage spike is wiped out by the diodes and the tach sees nothing. So when you connect the 2 separate negatives of the EDIS coil pack to the tach through some diodes, of course it won't work! And you can't just joint the 2 coil negatives together to the tach without diodes as that defeats the whole purpose of the 2 coils and might even damage the EDIS module.

So my plan is to build the circuit which I've added to the main posts. Using a gutted relay (using the relay coil only) and a transistor, hopefully this will simulate the original ignition coil (relay coil still makes a magnetic field, which will collapse when switched off and make the same high voltage spike) The signal to turn the transistor on and off will now have to come from the Megajolt ECU, not the coil pack.

Fingers crossed this will work, if it doesn't then I'm out of ideas on how to drive the stock tacho with EDIS

[Gannon]

Why not use a simple op-amp in inverting mode from the tach output of the edis module and use it to turn the positive pulses into negative pulses?

[Silverbullet]

Why not use a simple op-amp in inverting mode from the tach output of the edis module and use it to turn the positive pulses into negative pulses?

In theory you'd think that would work, but I'm willing to bet it wouldn't work with the stock tach because the tach needs that high voltage spike (maybe 20v or so in this case?) from the negative side of a coil as its magnetic field collapses. Also my previous attempts at making circuits with op-amps hasn't been very successful the transistor+relay coil idea maybe I can handle

Also, for anyone still reading; the above spiel about collapsing fields in electrical coils is exactly the reason why it is good to have a diode across the coil of any relay (some relays you can buy with this built in, or sometimes it is a resistor in cheaper versions) to protect any circuitry that might be downwind of a relay that could be damaged by that high voltage spike. Probably not so important in cars, very important in PCB's with relays.

[Silverbullet]

I know this conversion is done and dusted now but I just thought I should update the stock tachometer situation in this thread. As I said in earlier posts, the stock tacho doesn't work on the EDIS signals - I didn't end up doing the hacked relay trick because I was convinced of a better option. I ended up pulling the instrument cluster apart, removing the stock tacho PCB and making my own from scratch using the 555 timer IC chip. The 555 tacho circuit is as old as the hills; tried, tested, simple and effective. I initially had some problems after I made the circuit with it not working, or the needle being very jumpy and vibrating. It took me a long time to work out why - all the circuits for this you'll find online are just what some electronics whiz has dreamed up and what he thinks should work, most of them haven't even been tested on the bench let alone on a car

Here is the circuit diagram I initially followed:



This circuit has a number of problems:

1. The input resistor (15R) is completely wrong, with 15 ohms here the 9v zener is dissipating something like 4-5 watts! With most zeners being 1-2w rated I went through a few zeners before I realized what was happening. A 5k resistor here is much better.

2. The timing resistor and capacitor on pins 6 and 7 are are bad choice (especially for this application) This choice of values gives an output pulse of .001 seconds duration. The end result of this is a shaky/vibrating needle since there's too much off time between the output pulses going to the meter. I worked out the maximum on time I could have for each pulse at 10,000rpm was something like .012 seconds, so I changed the resistor to 9.1k ohm and the capacitor to 10 microfarad to get .010 second pulses. This is when taking a signal from 1 coil only out of 2 so I'm getting half the pulses than if I was reading off both coils.



After this it worked much better. To calibrate the circuit on the bench, I found a 240v to 16v a/c transformer and connected one line of the 16vac to the input, the other line to ground of the circuit. This triggered my circuit at 60hz mains frequency, which on a regular 4cyl car would be 3000rpm. On mine because I'm reading off of one coil, I calibrated it to 1500rpm.

I borrowed the oscilloscope I use at work and it can save screen grabs to USB so:



The blue line is the 60hz mains sine wave (stepped down to 16v) you can see as soon as the sine wave goes negative, the tacho circuit triggers and makes a positive pulse at the output for the set duration. If you count the squares, you will see it is exactly .010 seconds The constant pulses going to the needle movement is smoothed out by the movement giving a stable reading at the needle. As the input frequency increases (higher revs) the output frequency will increase and the needle will move higher.

If you're interested, this is the signal coming from the ignition coil:



This was with the probe at 10x division so each square represents 10v. You can see the coil sits at 12v approx until the EDIS module disconnects it from ground for about 3 milliseconds. At this time, the coil fires from the secondary to the spark plug but also there is a huge 40v spike on the primary. This is the spike I was talking about it earlier posts, you get this when you turn off any inductive load (coils) e.g relays which is why they have supression diodes. The 5v zener, 1k resistor and .1uf capacitor in the tacho circuit prevents this spike from damaging the 555 IC.




Okay so the last little bit was probably not necessary to explain and maybe too technical but I thought I'd post the scope screen shots anyway, so you guys can see what is really going on when I'm talking about pulses and duration etc etc. Oscilloscopes are great fun

[TOONGA]

Nicely explained Sam.

When is the car going to be finished

TOONGA

[El_Freddo]

That's crazy mate. Where did you learn all that stuff?

It was almost like learning a new language for me!

Top effort once again!

Cheers

Bennie

[Silverbullet]

Bennie - it's part of my job to understand this stuff at least to some degree Trust me it was like a new language to me too, took me ages to wrap my head around what was going on and this is a really basic circuit.

Jules, it will be finished when it's finished Hopefully in the next 6 months. There's alot of fiddly little things to do that take ages (like the tacho circuit ) I'm nearly ready to put the carpet in, just have to do 1 more front seat mount. Then it's all interior stuff...and exhaust...and front struts...well there's a bit more to do yet

[steptoe]

Hmm, the tute is not locked !

Read, read and re-read is definitely good advice.

Maybe watch this space >>>>>> [ ] for my attempt to follow Silverbullet Sam in an EA82GT application.

Sam has shared a lot of his learned experience in every aspect of his conversion with me over time , and I am still putting a lot of parts research for the best "off the (local) shelf " way of going about it. There are different coil construction, therefore different lead ends to deal with. Sounds like Sam enjoyed the home made lead task as much as finding his new engine ate a distributor gear

I have found local and US part numbers for the two coil types, a typical HT lead set donor vehicle available locally in Australia

A little gem I discovered , contrary to what is above , the EDIS4 modules can be found in something like 2002 Focus and 2001 Mondeo with ADR compliance plates.

Anyone tempted to join this very tiny club yet? 3,300 odd views of Sam's photo's - not all just me surely??

Having trouble confirming lead set component lengths to see if they contain something to suit the Spider intake needs - 42" has been a pain.

I have found some converters,, including Sam, have found that the old distributor location is a good spot to plant the new coil pack

The EA81 coil pack location in Sam's job is pretty central and a bit easier on lead lengths. The EA82 dizzy causes bloody long leads for #1 and #3.
To fit the coil pack in this same spot for an EDIS conversion, does not get away from the long HT leads.

EDIS comes in EDIS4, EDIS6 and EDIS8 just not seen 6 and 8 in Australia yet, so not just a four banger ignition system.

So, these coils to suit come in 4 and 6 pack, the V8 doubling up, using two coil packs. Amazon were offering two coils in a package, got me thinking... maybe, what if, if can mount a coil 4 pack close to each head, run short leads ?

Have ordered coils and V8 lead set with ends already made to suit coil , cut down to suit desired lengths and fit easy to fit plug ends.
Seems brainstorming with Sam, we came up with same idea about same time. This way, 8 leads allows for errors or spare lead set

TBC

[steptoe]

so much easier leaving password set into lappy

Got some part numbers n stuff to add as a bit of an update, though at time of writing I personally can't vouch for fit or work as I am relying on others - posts around the internet.

Pretty sure the EDIS4 modules I have are from 2002 Ford Focus and 2001 Ford Mondeo - all getting a bit thin on the ground.

I found someone's parts list quoting ignition coil as FD487 as one to get. If my understanding is correct this is type 1 that trigger wheels in the UK refer to and suggest and supply. I have looked into this one. Is a coil pack for a 4 cylinder. Three pin socket on it. coil,power,coil

FD487 only seems to have been fitted to AU 5.0 litre V8 1998-2000 and from what I can find , is a GOSS C190 or Fuelmiser and Delphi CC240
Each coil tower appears squashed with an exterior rib to lock the HT lead on.

Ordering from the US I have used a 1996 Ford Crown Victoria 4.6l V8 as the reference to get this squashed looking coil tower "type 1" coil
The V8 uses two 4 pot coils. A wide choice of brands over there too, found HITACHI [ A$57 plus GST] and HELLA [A$50 + GST] .

I chose HELLA, should possibly have gone HITACHI to be loyal
I also ordered the VR sensor for crank angle sensor CAS for same - hoping it all works in harmony.

Lead set for same V8 to get the correct fitting right angled coil end boots. An Australian option for leads source could also likely be the Ford AU 5.0l 98-2000

As for the other coil likely in Sam's project pics - it looks to be also in our Ford Focus of 2002 with a Fuelmiser packaged, Delphi labeled coil CC239, which correlates to being a GOSS C220. This , I think is "type 2" trigger wheels refers to, smoke stack smooth coil towers with a male centre pin.

I thought I might have been able to source locally, a lead set from a 2002 Focus, as Repco offered the squat, ribbed tower coil as an alternative, but ....

ever noticed some shop staff seem to dislike helping people work out part sources for projects? Unlike a hardware joint where you can go in and play with various bits n pieces like lego bricks to see what works - disturb nobody. The vibe and prices sort of drive me online and overseas.

I bought a trigger wheel from trigger wheels in the UK, recommended me to get the one with half inch hole, rather than their ring gear style.

An old machinist mechanic skimmed the rear pulley V down square and flush to take the ring gear he made out of the wheel.

Oddcomp from USMB wished he made his ring gear an interference fit rather than loose as each time he welded it and found development problems, loose fit was no longer his choice. It was his discovery of welding a trigger wheel to the outer damper of the EA82 turbo harmonic balancer was not a good idea as it started to slip on its hub - causing timing of CAS and missing tooth to go out. He had to cut his weld, re-align, weld n go gain.

Interference fit , loctite might mean no weld.

Using Sam, Oddcomp and a few other online experiences and that of my machinist - the trigger wheel attaches to the hub of the harmonic damper to avoid problems should damper outer balancer slip or fail. Using trigger on a rubber mount may also play with sensor gap between trigger teeth and CAS