Autosport Labs

I had a problem with weak sparking that may be related.
I set up the EDIS part alone and tried it with terminal blocks and wires everywhere and it worked fine while spinning the engine. Then I set to doing a more permanent job with a relay and fuse in the main supply. Trouble was that I only had a 2.5A fuse (blow at 5A) and thought that I would replace it later. Some days later (forgetting about the fuse) I tried spinning the engine again only to find that the spark was as weak as you-know-what. Strange thing is that the fuse didn't blow (presumably due to the on-off nature of the demand placed on it) but the resistance from it definitely appears to affect the spark...

My 20 year old Fluke is playing up right now (maybe it's the 20 year old battery?) but appears to indicate about .5ohms for each EDIS LV coil so it would seem logical to me that you would need a pretty good (ie low resistance) supply and earth to allow it to get it's full 12 volts and hence deliver a big fat (Greek?) spark... Especially as the revs rise.

Oh, and another thing just for interest... My (inductive) timing light works fine on cheap carbon cored HT leads, but only flashes occasionally when fitted around my nice new low-resistance 'Ferromax' cored leads...

TwoSheds

david jenkins wrote:I saw similar problems on my car - I even posted a similar question on this forum. The answer (for me anyway) was quite simple.

The EDIS coil is wired to fire 2 spark plugs at the same time. One spark gets a negative polarity impulse, the other gets a positive one. My timing light has a clip that goes over the plug's ignition wire and has an arrow that points towards the plug, suggesting that it expects an induced voltage in a specific direction.

If you have a similar sensor clip on your timing light, try turning the clip over on the cylinders you think are faulty, and see if the timing flashes improve. This may not be the answer to your problem - but it's a really cheap test before you spend any more money!

In my case, I decided to ignore the timing light result as the engine was running properly!

Let me know the outcome if you decide to try this...

cheers,
David

(apologies if this has been covered, but I did search the forum, but couldn't find it)

The above post is a good point worth noting by anyone using a strobe - surely all of us? Although I had read it and tried the suggestion, my 20-year-old strobe wouldn't work on leads coming from coil-pack posts numbered 2 & 4 no matter which way round I put the pickup.
So off I toddled to Halfords for an extortionately expensive new strobe (£40!), which incidentally had possibly the worst bit of design I have seen for a long time in that the advance adjustment dial was a loose and floppy analog thing which I wouldn't trust to be accurate to within 10deg! Hardly the kind of gear that you would want to test/set-up a state-of-the-art ignition system with! My old strobe has no adjustable offset, it just lights when it 'sees' a 'lead event' so at least it is a known quantity in that respect...

Anyway back to the plot:

The new strobe didn't work on 2 & 4 either

So a little experimenting into the evening ensued and I came up with this:

1 & 2 will fire both strobes, 3 & 4 will not (save for occasional flashes). This is true of both coil-packs on my V8.

In my (V8 ) setup, in order to get a decent lead layout, the number 1 cylinder is sparked by the number 3 coil-post and so will not drive my strobe. Not a problem once you know that though, because I can fire the strobe using the wasted spark on my number 6 lead (which is connected to the number 2 coil-post)

Problem solved (for me at least )

So - in the middle of the night I am lying abed wondering why, and I came up with the following:

(caveats - I know very little about electrics so this might be a pile-0-poo )

Each coil-pack contains two coils - so let's consider one of them:

No matter which plug is about to fire, the charging voltage applied to the coil is the same polarity.
When the circuit is opened by EDIS in order to generate the spark, a rapid voltage rise occurs between the two ends of the coil. This bit of the system currently (pun) has no knowledge of where the vehicle earth is.
To complete the HT circuit a spark has to occur across both plugs - in between these plugs the voltage has to be at vehicle earth.
Therefore one HT lead must always go negative with respect to the vehicle earth, and one must always go positive.
I think that, since the electronics in the strobe are grounded ie connected to the battery; maybe the strobe pickup is designed to trigger on a rapidly rising voltage and hence will only work on one of the two leads connected to a coil.

My two penny worth.

TwoSheds

I think your problem is here!, I happend the same problem.



check the gap-feeler (sorry my english ), 1mm it's OK