Ignition system with repetitive sparks

mwman · Post by **mwman** » Wed Oct 10, 2007 1:16 pm

I have found reading about the EDIS module on the net, that it is possible to have the unit perform repetitive sparks.
The infomation suggests this is available at 1200 RPM and below. I wonder if it could be considered as a possible "upgrade"?
This link details the patent on the system.
http://www.answers.com/topic/ford-edis
Regards
Simon

Post by **brentp** » Wed Oct 10, 2007 3:26 pm

Hi Simon,

As posted in the other thread, the Multiple spark discharge feature was intended by ford for low RPM operation (< 1800 RPM) and I believe, to improve combustion efficiency and emissions. Not to say it isn't a feature worth adding to the firmware- there haven't been a lot of users clamoring for it, as I believe most have been valuing the MJLJ+EDIS upgrade primarily for it's high performance benefits.

I will put it on my to-do list, but I have some other higher priority items going right now- currently the rev-limit module- and other big projects.

Thanks for the note!

Regards,

mwman · Post by **mwman** » Wed Oct 10, 2007 7:30 pm

Thanks Brent, I did not know the module had that function, I came accross it quite by chance.

I can understand that there are a lot of features people want added!

I think it would be useful for the leaner burn engines where the charge is hard to ignite.
Simon

KLAS · Post by **KLAS** » Thu Oct 11, 2007 8:21 am

honestly, i would love such a feature, but i think it would be of much more use if it will go up to 3000RPM or even more.

if there is an easy way to activate this i will use it. but how to find out if the EDIS box will support this? any known part numbers?

merlin · Post by **merlin** » Fri Oct 19, 2007 12:44 am

brent,
Just read this tred now this might be just the solve for a problam I am having at the moment is there anyway I might be able to rig this to work. I have kinda got around the problam which is high Co2 at idel by opening the plug gap up to 1.05mm to hold the spark for longer but multi spark would be a much better way any help on this would be great.
Regards,
Paul.

mwman · Post by **mwman** » Fri Nov 02, 2007 9:21 pm

Here is the US patent with explanation.

http://patft.uspto.gov/netacgi/nph-Pars ... PN/5014676

And the links from the answers site.

http://www.answers.com/ford%20-edis

Simon

hcp474 · Post by **hcp474** » Sun May 25, 2008 1:51 pm

This feature is one i'm very interested in, i've started looking into methods of achieving it using separate hardware, an achievable method is to use a CPLD to create the apropriate signal using the input from the MEGAJOLT or any other ECU and a toggle to activeat / deactivate.

This feature is of particular interests for 4x4, in my case a 1969 landrover as the long stroke engine runs at rpms where this is applicable more than 50% of the time.

all my time and £ are being used getting it back onto the road, so i've not got the design to a functioning point yet. i will post once i've got something running.

The ultimate aim is to build a CPLD module that will do all of the timing functions much like the EDIS module itself, so that i can build as complex or simple ECU to feed it the advance angle required an it does the timing.

David

DannyP · Post by **DannyP** » Mon May 26, 2008 1:31 am

"The EDIS module has the capability of performing recurring spark, more commonly referred to as Multiple Spark Discharge. The latter is usually associated with CD ignition boxes. This feature was introduced with the 1990 1.9L Escort/Tracer engine. The ECU enables the MSD below 1800RPM on these engines. To signal to the EDIS module that MSD is desired, the SAW is lengthened by 2048us on 4/6/8 cylinder units, and 1024us on 10 cylinder units. The EDIS module can achieve up to 3 sparks per cylinder event using this feature. "

From here:

http://www.dainst.com/info/edis/edis.html

Post by **brentp** » Mon May 26, 2008 6:32 am

Hi All,

looking over the firmware code it seems that it would be pretty easy to accommodate the pulse lengthening required to activate multiple spark discharge as outlined in the EDIS specification.

What it will look from the user's point of view is that you would have an additional option in the ignition configuration which would enable/disable multiple spark discharge under 2000 RPM (or so).

I'll put this on the list of things to do- I should be able to test this soon after the V4 release. All MJLJ hardware revisions (V2,3,4) will be able to receive this enhancement.

DannyP · Post by **DannyP** » Mon May 26, 2008 10:52 am

I love all this open source stuff!!!!

People dream it, Brent writes it(like he has nothing better to do!), and then there it is, an extra feature we all glom up and use. Excellent!

hcp474 · Post by **hcp474** » Mon May 26, 2008 7:48 pm

Sounds good to me Brent, Many thanks for adding it ot the to-do list.

david jenkins · Post by **david jenkins** » Mon May 26, 2008 9:26 pm

What are the benefits of multiple spark at lower revs? The EDIS/MJLT combination generates a pretty substantial spark in standard form!

hcp474 · Post by **hcp474** » Tue May 27, 2008 12:50 pm

At lower revs the compression comes on slower which means there is the possibility that the mixture will not fully burn, the repetative spark means a fuller/more complete burn should be achieved. This improves both power output and improves the emissions of the system.

This should be a real boon for low revs in combination with a LPG system (which takes longer to burn anyway; hence the increased firing angle).

David

hcp474 · Post by **hcp474** » Tue May 27, 2008 12:51 pm

At lower revs the compression comes on slower which means there is the possibility that the mixture will not fully burn, the repetative spark means a fuller/more complete burn should be achieved. This improves both power output and improves the emissions of the system.

This should be a real boon for low revs in combination with a LPG system (which takes longer to burn anyway; hence the increased firing angle).

David

alhbln · Post by **alhbln** » Sat May 31, 2008 3:54 pm

To the best of my knowledge, multi spark ignition was invented by Christopher Jacobs (Jacobs Electronics) and that patent has expired a long time ago. MSD, Mallory and Crane all do multi spark capacitive ignition systems. Havent read the patent docs so it might be that the patent applied to the combination of capacitive discharge ignitions with multi spark capability.

I'm not so sure that the multi spark approach is always as effective as the marketing wants us to believe. I have installed several aftermarket items (MSD 6AL, Mallory Hyfire 6AL) in different cars, and with low RPM big capacity engines there is an instant improvement. As exampe we have installed an MSD 6AL in an Aston Martin V8 with 5.3 litres engine and the car now runs much better and smoother than before, throttle response is also much better.
We also installed a Hyfire 6AL in a race bred 2.4 litres high reving engine and did some rolling road tests and there was no improvement in torque and horsepower (got an additional 5 NM at 3000 rpm, well ok). The engine runs smoother, though.

Would assume that multi spark systems help a lot when replacing old inductive setups and covering worn out distributors and non optimal advance curves but cleary we dont have such a problem with an Megajolt setup