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initial testing (didnt work!)
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"Since the EDIS module can operate the engine by itself in a "limp-home" mode, with the advance fixed at 10 degrees BTDC, it's recommended you install the EDIS module and coil packs first, and then verify your engine runs before wiring in the MJLJ."

i have all the plugs wired to the coil pack, the edis module nd the vr sensor, but the mega jolt is not connected to anything, is that what the above statement from the installation guide means?

On the diagram of the edis plug the SAW and PIP wires are shown as "To MJLJ" should they be connected to it at this stage?

any advice much appreciated, thanks,
Tom

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Yep, exactly that...leave the MJLJ in a sealed package well away from the engine so there's not even a chance that it is in the circuit Cool

So yes, the "To MJLJ" PIP and SAW wires won't be connected to anything.

You should be able to start and run the engine, with rock solid 10BTDC wiring with just the trigger wheel, VR sensor, EDIS module and coilpack

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thanks for the reply, but i still have no spark. I did some reading and found this reply to a similar situation:

"No spark at all indicates an EDIS problem so let's get back to basics:
- take the MJLJ out of the car completely
- take all the plugs out and all but one off the ignition leads
- rest the remaining one on the lead on the block, so that the outside of it is earthed
- turn the engine over - any sparks?

Assume no, so....
- check the wiring at least 3 times
- check earths
- (silly question - you have got one of the teeth missing on the trigger wheel haven't you?)
- measure some voltages during cranking - 12v on EDIS pin 8 and on centre connection of coil

Report back..."



I tried all of these. my grounds are good. i have them all conected to the same point which is additionally connected directly to the -ve side of the battery. I have grounded the coil from the metal pads on top near its mounting holes to this same place also.

I have 12V at pin 8 and to the centre of the coil.

I have also checked accross the terminals of the VR for continuity and it has it, so thats good.



Are there other ways i can check the components of the sytem, they were brought second hand so may be at fault.



Thanks,
Tom

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It seems qiute common for people to get the VR connections arse-about-face, and this would stop a spark being generated. It's worth swapping them over, just to see.

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i tried this, still no joy. i really think one of the edis components are not working, is there any way i can check them?

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RAT wrote:
thanks for the reply, but i still have no spark. I did some reading and found this reply to a similar situation:

"No spark at all indicates an EDIS problem so let's get back to basics:
- take the MJLJ out of the car completely
- take all the plugs out and all but one off the ignition leads
- rest the remaining one on the lead on the block, so that the outside of it is earthed

- turn the engine over - any sparks?
<cut&shut>

Thanks,
Tom


Hi,
The statement in bold (above) made me wonder if I understand anything at all... You see with a wasted spark I thought that there is no earth on the HT side of the coils and that the circuit is made through the other lead (per coil) so that to test for a spark one would have to place the two HT leads (or plugs) from one coil so that their ends are in proximity, something like this:


Or am I completely up the wrong tree here?

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Wrong tree I'm afraid Sad

Look at the diagram here:
http://www.autosportlabs.net/Ford_EDIS_technical_information

A given spark plug doesn't know it's in a wasted pair - it just gets a 40kv pulse on its centre electrode that jumps the gap to the earthed prong that is earthed by the plug thread in the head.

The diagnostic test just puts the plug on top of the engine so you can see the spark - and you have to lay the plug on the block to get the earth...if it's left in free space you'll not get a spark.

Who cut those plug leads? Sacrilege Confused

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MartinM wrote:
Wrong tree I'm afraid Sad

Look at the diagram here:
http://www.autosportlabs.net/Ford_EDIS_technical_information

A given spark plug doesn't know it's in a wasted pair - it just gets a 40kv pulse on its centre electrode that jumps the gap to the earthed prong that is earthed by the plug thread in the head.

The diagnostic test just puts the plug on top of the engine so you can see the spark - and you have to lay the plug on the block to get the earth...if it's left in free space you'll not get a spark.

Who cut those plug leads? Sacrilege Confused


Sorry to be thick, but I still don't get it...

The schematic that you point to makes no reference to the internal wiring of the coilpack, but having tested mine I found that the pairs in photo (which I had assumed are connected to opposite ends of the HT coils) have 19 K ohm (ish) between them, but each of the HT leads is showing open circuit to earth.

So how (I thought) does one lead spark to earth without then going back up the other plug/lead?

In my ignorance I have assumed that the current would be induced in the coil, go out down one HT lead, jump the plug-gap, go through the head, jump the other plug-gap (backwards) and then back up the other plug lead and to the other end of the coil. I just can't see it working any other way for the moment, but then I am still only just starting to climb onto the shoulders of giants after all!

Thanks for the help with this.
Signed
Confused of Yorkshire

p.s. The leads are off a Mondeo and are probably 18 years old.. And even the longest was too short for the shortest on my V8, so I think that trashing (to get the terminations) them was justified in this case Wink

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Each coilpack will energise the HT leads in pairs, with 40kV appearing at a pair of HT terminals simultaneously, but they are not dependant on each other to work.

To check the spark:
- remove all the plugs to ease cranking
- have 3 HT leads going 'nowhere' i.e. no plug inserted in end of lead
- in sert plug in end of 4th lead, and rest body of plug on engine block so the body is earthed
- crank engine, you should see a nice spark across the plug gap

Hope this is clear,
Rich.

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TwoSheds wrote:
So how (I thought) does one lead spark to earth without then going back up the other plug/lead?

Because each spark plug is earthed by being screwed into the engine block. If "your" spark is earthed by the other end of the HT coil then that 40kV would have to be present on the engine block as it passed through it - and that is hard to believe Cool

The subtlety on the diagram is the earth that is drawn between the outer casings of each spark plug pair.

After a bit of Googling, details on the HT side of wasted spark coilpacks (or even standard single coils) isn't easy to find - almost everywhere it just says that the HT coils produces the volts and the spark happens!

Your measurements suggest that the two plugs that fire at the same time (1/4 or 2/3) are connected to either end of the same HT coil ... and I measured the same on one of my coilpacks. So I assume that each end of the same coil gets the 40Kv spike when the primary current collapses and this is dissipated by sparking through each connected plug to earth...

...but maybe I'm looking for a giant's shoulder to climb onto as well Wink

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TwoSheds wrote:


... I have assumed that the current would be induced in the coil, go out down one HT lead, jump the plug-gap, go through the head, jump the other plug-gap (backwards) and then back up the other plug lead and to the other end of the coil.


This is as I understand it...

Also see (scroll down in the document, fig. 3-31)
http://www.autoshop101.com/forms/h41.pdf



Not a Giant,



Last edited by brentp on Sat Jan 12, 2008 9:44 pm; edited 1 time in total

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http://www.autoshop101.com/forms/h41.pdf

Thanks for that Brent - though Fig 3-37 is better I think...

I still wonder how the accepted method of testing (described above) works though... Ah well sometimes it's enough that it does Smile

Cheers,
TwoSheds

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I worked it out when I woke up in the middle of the night thinking about it (Sad) when I realised that the spark must be in different directions in the two attached plugs. Honest!

And Fig 3-37 confirms it. Yay!

I've no idea what the diode is that is shown in the HT coil - measuring my coil doesn't indicate that I have one.

The circular discharge circuit isn't mandatory to get a spark in one plug only - I've run many tests on EDIS units connected to a coilpack on the bench with only one lead and plug connected and it sparks away just fine.

It's (maybe) interesting to know if all plugs are designed for "dual-direction" usage, as we have. In the good old days, the spark was in the same direction for every plug and the physical design may have taken that into account. So 'old' plugs might not be most appropriate for wasted spark use....maybe

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MartinM wrote:

I've no idea what the diode is that is shown in the HT coil - measuring my coil doesn't indicate that I have one.

There is no sign of a diode in mine either, but then again the diagram is from Toyota. I guess that the diode may be to stop it from sparking when the primary is switched on?, and that you wouldn't need this if you arrange for a soft-start from the EDIS controller...

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Related to reversed polarity across coil-pack plug plugs pairs, I recall seeing a discussion about single tipped platinum plugs wearing differently from cylinder to cylinder in a wasted spark setup, but searching recently I could not find any supporting information... ahh well. Rolling Eyes

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