EDIS wiring question

[GS guy]

Setting up a Subaru engine with MSII V3, relay board and EDIS ignition.
The Megamanual shows switched 12V coming into pin 8 on the EDIS module - and appears to be fed from an owner installed main relay (not part of MS or the relay board). It shows a 15A fuse on this line. This same line feeds power to the coils. Would there be any problems feeding this "main relay" from the battery cable at the starter? My battery will be at the opposite end of the car from the engine, and since I already have to run a large gauge cable to the starter it seems like a much more convenient location to tap for MS and EDIS power (through a relay controlled by the ignition switch). Only concern is possible V-drop during starting coming off this terminal? Should I run a dedicated feed wire directly off the battery instead?

If I'm following this correctly the switched power line just Tees off to connect to the EDIS module? The 15A fuse implies much larger current than it looks like the EDIS module plug wiring can handle? What wire gauge should be used for this switched power line? 14AWG? or 12AWG?

I'm feeding COPS with this wire - so when it is split to go to two pairs of coils, can the wire gauge be reduced at the split to something smaller(maybe one gauge size)? Or should I stay with the original wire gauge throughout - back to pin 12? The wires coming out of the EDIS module plug seem way undersize to be powering the entire ignition!

For the ground wire coming off pin 9 - what gauge wire should be used for this? And this should ground directly back to the engine block? Should the relay board also ground back to this point?

Sorry for the 20-questions! I read and re-read the information on installing these systems, plus pages of Ignition forum postings and couldn't find answers to these questions.
Thanks!
Jeff

[Heribert]

The main part of the " EDIS" current goes thru the coil pack plus feed, back to the EDIS module thru the
coils in the coil pack / interconnecting wires , thru the internal switching transistors in the EDIS module
and then to ground thru the EDIS ground wire, This needs to be=> 1,5sqmm wiring.
Sorry for going metric on you , I know about AWG sizes , but hate to guess, and do not have the table handy.
And power supply MUST be the switched power supply so that you have +feed during key on and cranking.
The plus feed to the EDIS module can be smaller, choose 0,75 sqmm.
And be sure that you install the filter cap close to the coil pack +feed directly to ground.
EDIS 4 current draw at 6000 rpm is less than 4 Amps, most likely around 2,5 only.
The fuse is to protect from cable fires, not the match the actual service current draw.
I would use a separate feeder wire from the battery to a power on relay/ distribution
point that sits in the engine bay or under the dash. Put a fuse at the battery connection point, rated at the
feed wire 1 sec amp rating.
Sneaking power from the wire that feeds the starter/alternator +wire is also possible but the day you have a weak
battery , this means trouble.
And the MS box it probably more sensitive to low voltage than the EDIS. I have made some low voltage tests on an
EDIS 6 on the bench.
And it sparked away happily at 7,5 Volts and 600 rpm!

Heribert

[GS guy]

Thanks for the info Heribert. I came across a neat conversion chart (with additional current and wire size info) here:
http://www.rbeelectronics.com/wtable.htm

Nice chart. Looks like your 1.5mm2 wire size equates to between 14-16 AWG, so 14 it is.

Your recommendation about the capacitor brings up an interesting point. Running COPS I no longer have just the single coil, but (4) instead and not closely spaced to each other! Fortunately, the pairs wired in series are on a single head (for each side of the engine), but still no way to get that single capacitor on each coil as was originally. I guess the options are to run individual capacitors on each coil, or run a capacitor for each series wired pair of coils. The source that has run this set-up on a Subaru didn't use the capacitors at all, but this was for a sand buggy application - so not likely using any kind of radio? I may start without, then experiment adding one or more capacitors to tune out noise.

Jeff

[Heribert]

Capacitors are easy to understand at least in general terms.
What is not so obvious is that that the pretty fast transients
that occur at an ignition event vith even 20 cm ( 8") of wiring
has a pretty high impedance and can create unwanted disturbance.
So , if you have any doubts at all , try to get a FORD EDIS cap
or similar engine bay graded units up real close to each COP + feed wire.

I just scoped an EDIS 6 on a test bench for fun. At 3000 rpm I got a
large transient about 1/3 in on the hi level of the PIP signal. There was a dropout
going down to +1,5 V.No caps installed.

Power supply with 14,2V/ >20A cap and excellent filtering. Leads from
PS to EDIS Coilpack was some 800 mm.
Adding a 10 µF mylar cap directly at the coil pack removed the transient
totally.
My scope is Tektronix 465, so can not download pics! Sorry for that,
it would have been quite instructive!

Heribert

[GS guy]

Another couple of questions with EDIS hook-up and mounting - right to the point:
- Module mounting - is the unit fairly vibration resistant, can it be mounted directly to the car chassis?
- What about heat dissipation, or RF output? Anything I should keep it away from (like the Relay board, or other electronics)? Or just put it anywhere convenient where it doesn't see too much heat?
- PIP/SAW wiring - do these need to be individual shielded? Can a twisted pair inside common shielding be used?
- Quick disconnects on shielded wiring: I need to install QD's on the PIP/SAW wiring. I can bring an extra pin (or 2) in the connector for shield connection pass-through - will this cause any problems with noise? Any advantage on location of the QD?
- On a similar note, the VR sensor has a factory quick-disconnect (with extra shield wire) I want to re-use. Any issues with noise with that set-up?

I'm trying to sort the wiring now and want to keep as much of the original engine wiring harness as I can, especially as most wires already have a quick disconnect in-line plug that can be re-used. Just have a concern about shielded wires.

Thanks,
Jeff

[hamiltonguitars]

Another couple of questions with EDIS hook-up and mounting - right to the point:
- Module mounting - is the unit fairly vibration resistant, can it be mounted directly to the car chassis?
- What about heat dissipation, or RF output? Anything I should keep it away from (like the Relay board, or other electronics)? Or just put it anywhere convenient where it doesn't see too much heat?
- PIP/SAW wiring - do these need to be individual shielded? Can a twisted pair inside common shielding be used?
- Quick disconnects on shielded wiring: I need to install QD's on the PIP/SAW wiring. I can bring an extra pin (or 2) in the connector for shield connection pass-through - will this cause any problems with noise? Any advantage on location of the QD?
- On a similar note, the VR sensor has a factory quick-disconnect (with extra shield wire) I want to re-use. Any issues with noise with that set-up?

I'm trying to sort the wiring now and want to keep as much of the original engine wiring harness as I can, especially as most wires already have a quick disconnect in-line plug that can be re-used. Just have a concern about shielded wires.

Thanks,
Jeff

Hi jeff:

I've had my EDIS-4 mounted on the inside fender of 1959 austin healey sprite for 3 years with no issues weather or vibration, so I think your safe.
If you use a 2 conductor (i used a 3 conductor and didn't use the 3rd wire)shielded cable it shouldn't have any problems RF, heat or otherwise (ovbiously, don't set it on your headers).
I've been using the factory connector also with no worries.

rod h

[GS guy]

Thanks for that Rod!
I'd posted similar questions on the sensors section and gotten some additional response there.
I decided to use the original ignition module mounting bracket that came with the module to mount it to the chassis. I was trying to figure out some sort of custom bracket to mount the module, but needed something T-shaped to position the module above a frame member. Racking my brain how to do it - then I recalled the OEM bracket it was originally mounted on. I'd "binned" the bracket, thinking I could do something a little nicer! The bracket "angled" the module, I suppose to come off an inner fender or something. I simply straightened the angle, making it a direct 90 degree mounting plate, it's going to work perfectly! Even has a tab off one end with a short stud, going to re-use this with a loop clamp as a strain relief for the wiring coming off the module.
I'll be bolting this directly to the frame on my car - a tube framed buggy.

Cheers,
Jeff