Troubleshooting EDIS / coilpack problem

EDIS and Megajolt installation related topics. Be sure to review the <a href="http://www.autosportlabs.net/MJLJ_V4_vehicle_installation_guide">Vehicle installation guide</a>

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spetom
Posts: 30
Joined: Sun Jun 15, 2008 3:35 pm

Troubleshooting EDIS / coilpack problem

Post by spetom »

This is a continuation of the problems mentioned in Nitropixie's thread: http://www.autosportlabs.org/viewtopic.php?t=1970.

Briefly, using a timing light to check the advance, I noticed that while plugs 1 and 2 produced gave good, regular pulses, 3 and 4 were irregular, frequently missing beats.
I thought it was the coilpack, but I've now tested another unit, and it's exactly the same.
I've tried swapping the plugs, again with no difference.

Which I suppose narrows the problem to either being the connection between EDIS and coilpack, the EDIS itself, or the timing light (which I can't understand would really be at fault - it should work identically with each plug, shouldn't it?).

I'll do some further tests tonight, but is there any other possible explanation, or recommended test I can do to quickly narrow the possibilites?

spetom
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Post by spetom »

Further tests: swapping the wires around had no effect, so it isn't the connection.

Swapped around the coilpack connections and the plugs, so what was going to plug 1 was going to 3 (and vice-versa), and 2 was going to 4: instead of 3 and 4 having problems, 1 and 2 now did, with 3 and 4 being fine.

I also disconnected the MJ, just in case that was having some effect - it wasn't.

So I'm guessing the EDIS is at fault. Is there anything that could effect the EDIS? Does the trigger wheel play any part here?

spetom
Posts: 30
Joined: Sun Jun 15, 2008 3:35 pm

Post by spetom »

So maybe it's nothing at all. Browsing other MegaJolt forums, I find this:
http://www.locostbuilders.co.uk/viewthr ... ssage=none
Two things to check:

Are you checking it with a clip-on timing light? If so, 1 lead from each pair (1-4, 2-3) will trigger a good flash, the other one won't. It looks like one lead is faulty, but if you take the plug out it'll spark just as well as the other.
:roll:

alexander
Posts: 246
Joined: Sat Jan 19, 2008 4:33 am
Location: sydney, australia.

Post by alexander »

i think the problem might be simpler than that...
the timing light clip has a coil of wire in it, in which a voltage is induced by the current flow in the lead.
many timing lights only work properly when the clip is clipped onto the lead, the 'right' way.

if you are getting intermittent flash, try taking the clip off, rotating it 180deg,and clipping it back on.

re the prior quote, i dont believe there is any truth in the idea that one lead will give a good 'flash', and the other not, on twin coil packs.

regards
alexander.

spetom
Posts: 30
Joined: Sun Jun 15, 2008 3:35 pm

Post by spetom »

Thanks Alexander,
I'm fairly sure I've got the clip on the right way - on the model I have, it's got a little arrow indicating the direction.
I've emailed the guy who made that comment in the hope that he can explain it further. Maybe it's just a quirk of certain models of timing light.

As far as I can tell, all plugs are firing correctly. There's no indication that sparks are being missed, other than the timing light - the engine runs fine.
I'll probably pick up one of those plug checking things that goes between the plug and the head, just to be sure.

david jenkins
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Post by david jenkins »

Hi Tom,

I'll answer your question here, rather than reply to the e-mail!

As far as I understand it, each side of the coil (e.g. 1-4, or 2-3) fires together, sending a negative spark down 1 lead, and a positive one down the other. The timing light's clip is designed to react to a pulse of a particular polarity, so it'll give a good signal on one lead, and a poor one on the other.

In my case, I had clipped onto the lead for number 1 cylinder and couldn't get a decent flash. Of course, I thought the worst and decided that there was something wrong with my ignition system! Common sense came along later - I took the plug out and looked at the spark, which was big, fat and hot - so the ignition system was working properly after all.

I have an old-fashioned timing light somewhere in my garage, with a sensor that goes in-line with the plug lead - one of these days I might try that out. In the mean time you could try turning the sensor clip over on the plugs where the flash is poor, so the little arrow points in the 'wrong' direction.

I could be talking complete garbage - but that's how it worked out for me! :D

cheers,
David

spetom
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Post by spetom »

I should have known you'd have an account on here David! Sorry for referring to you as 'the guy' :lol:

I'll try reversing the clip on plugs 3 and 4 when I get back home. Re-reading Alexander's post, this is also what he suggested - I'm kicking myself for not testing it out this morning!

alexander
Posts: 246
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Location: sydney, australia.

Post by alexander »

david jenkins wrote:
As far as I understand it, each side of the coil (e.g. 1-4, or 2-3) fires together, sending a negative spark down 1 lead, and a positive one down the other.
cheers,
David
while we are talking about it, that is exactly how i understand it too. each half of the twin coil pack is a single coil with a HT lead connected to each end. the current flow is, indeed, out one lead, from spark plug center electrode to earth, from earth to center electrode in the 'other' spark plug, back up the other HT lead, and through the coil. so current flow will always be opposite in the two paired plug leads. the coil secondary in these wasted spark coils is not connected to battery voltage at all, as they are in a coil/distributor setup.

which raises a point worth remembering: if you take one lead off, you are killing two cylinders. the old school method of pulling off leads, one by one, to find a 'bad' cylinder, wont work in the same way with a wasted spark setup.

regards
alexander.

david jenkins
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Post by david jenkins »

alexander wrote:
which raises a point worth remembering: if you take one lead off, you are killing two cylinders. the old school method of pulling off leads, one by one, to find a 'bad' cylinder, wont work in the same way with a wasted spark setup.
That hadn't occured to me! Could be very confusing, if you didn't know... :)

spetom
Posts: 30
Joined: Sun Jun 15, 2008 3:35 pm

Post by spetom »

Thanks for the help everyone. It was indeed a problem simply solved by reversing the direction of the clip!
Who knows what else I'd have pulled apart before I was aware of this! :lol:
Thanks again.

Fiddler
Posts: 15
Joined: Tue Dec 02, 2008 3:28 pm
Location: Devon UK

Post by Fiddler »

Hi.
Hope you don’t mind me latching on the end of this coil debate as there seems to some experienced types contributing here.

I have an EDIS ready to go on a 2 cylinder 2 stroke. I think I need one output (not both)
from each coil to get a spark every 180deg.
My question is, what is the best thing to do with the unused side of the coil? Is it ok to just leave it blanked? Perhaps earth it or connect to 12v? Perhaps a dummy plug? I first thought it would be a good plan to connect each end together to get a double sized spark but +HT +(-HT)=0 I think.

Any suggestions

Vince


(I put something similar in Q&A section)

Dean924s
Posts: 227
Joined: Fri Nov 07, 2008 2:57 am
Location: USA - MA

Post by Dean924s »

Fiddler wrote:Hi.
Hope you don’t mind me latching on the end of this coil debate as there seems to some experienced types contributing here.

I have an EDIS ready to go on a 2 cylinder 2 stroke. I think I need one output (not both)
from each coil to get a spark every 180deg.
My question is, what is the best thing to do with the unused side of the coil? Is it ok to just leave it blanked? Perhaps earth it or connect to 12v? Perhaps a dummy plug? I first thought it would be a good plan to connect each end together to get a double sized spark but +HT +(-HT)=0 I think.

Any suggestions

Vince


(I put something similar in Q&A section)
I would look for a coil that has only a single output. Something that would be used on a COP set up. You could try the coils that are used on the Ford modular v8's that use the COP set up. My 2000 expedition with the 4.6 has them. They are also very small and if you could figure a way to mount them on the plug you could eliminate plug wires all together. Otherwise just get two single pole MSD coils they sell for about $30 each at the local parts store.
Respectfully

Dean

alexander
Posts: 246
Joined: Sat Jan 19, 2008 4:33 am
Location: sydney, australia.

Post by alexander »

vince, interesting question!

if i correctly understand the way the coils are constructed, then you definitely cannot leave one side of the coil blank. the current flow in each coil is through the coil, down one ht lead, throught the spark plug, through the head, through the other spark plug, back up the other spark lead, and back into the coil. this is different to the traditional coil. this means that you must have both leads connected for current to flow at all.

so, what to do? i think you need to have the other side of coil attached to the head to complete the circuit. perhaps just pushed onto a suitable bolt or similar which is earthed onto the motor?

regards
alexander

Fiddler
Posts: 15
Joined: Tue Dec 02, 2008 3:28 pm
Location: Devon UK

Post by Fiddler »

Thanks Alexander.
I thought the ford coil pack may be centre tapped to the case but the meter shows this is not so therefore leaving it open is not an option. I think it will be ok if I ground one side and this was confirmed by a bit of bodging in the workshop.

Dean.
I like the idea of COP but my plugs are very exposed so may end up with a ugly mounting arrangement. It would have to put up with the serious pounding in a jetski. Brent suggested coil-near-plug. What vehicles might I find these on, bearing in mind I’m in UK. I don’t think I’ve ever seen an Expedition 4.6. I suspect modern bikes may have neat coil-near(or on)-plug units. I will keep my eyes open.

Cheers
Vince

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