tom_loughlin
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 posted on 8/1/05 at 04:47 PM |
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spark (or lack of..)
still having trouble getting the beast to run....
there is 11kV coming out of the coil, but still no spark...
yesterday i spent a happy day getting the complete loom out of a sierra, which i wired in, and still having the same problem. i have tried all plugs,
and another spare, and still have the same probs.
tried a plug directly from the coil and earthing it - no joy!
id love to get the thing running before tonight, as im going back to bristol tomorrow, and wont be able to do any more car till easter 
thanks chaps
Tom
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Jon Ison
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| posted on 8/1/05 at 04:58 PM |
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may be a stupid idea espcialy if its turning over on starter motor but is the engine earthed ok ?
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tom_loughlin
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| posted on 8/1/05 at 05:03 PM |
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yeah, as far as i can see, everything is earthed - i.e. when i touch my mutlimeter to the engine, and the batt for instance, it reads a voltage.
the thing i done get, is that there is a massive voltage coming from the end of the HT lead, but no spark.
V. confused
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studon
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| posted on 8/1/05 at 05:25 PM |
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Sorry I dont have a solution but wanted you to feel assured you are not the only one!
Im having the same problems with mine at moment!
So just as keen as you to hear some ideas.
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Rob Lane
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| posted on 8/1/05 at 05:42 PM |
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By a large voltage from lead, do you mean end of coil lead ?
Does applying coil lead close to an earth point give you a spark?
If so, what about rotor arm and cap ?
This distributes the spark to plugs.
Is rotor arm correct and on dizzy drive OK?
Is drive turning ?
Is carbon pin still intact in top of dizzy cap?
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paulf
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| posted on 8/1/05 at 05:48 PM |
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How do you know it is 11kv?.It should be more like 40 kv if working correctly.
11kv would spark a plug in open air but would not be enough to fire under compression.
paul.
[quote there is 11kV coming out of the coil, but still no spark...
tried a plug directly from the coil and earthing it - no joy!
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theconrodkid
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| posted on 8/1/05 at 06:04 PM |
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if you got low kv then its a coil/king lead prob,all the other bits do is switch
who cares who wins
pass the pork pies
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stevebubs
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| posted on 8/1/05 at 07:13 PM |
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Connect the output of the coil to a plug and hold against the block.
With your other hand, connect a wire to the -ive terminal of the coil.
While watching the plug, touch this wire to ground - you should see a spark (assuming the ignition is on)
If you do, then the coil is OK and you need to be looking at the dizzy very carefully.
First check for continuity between rotor arm and cap (put one side of a multimeter (checking resistance) on the coil lead, then test each of the other
leads by hand). When you test each of these, turn the engine over by hand so you can line the rotor arm up with the plug terminal.
If this is OK then your spark delivery is OK.
Next, take the cap off and place a multimeter to check the resistance on the trigger wire wire into the dizzy. Connect the other lead to earth.
Slowly turn the engine over and you should see the points opening and closing.
Resistance should go down to virtually nothing. If not, check you points gap and it may be worth rubbing the contacts with a bit of emery cloth to get
rid of any dirt / carbon build-ups.
If all this is OK and you still have no spark, then I'd recommend swapping out the capacitor as this is most likely to be the root of the
cause.
(note - a fault capacitor may also give out the odd spark - especially when you first turn it over)
HTH
Stephen
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tom_loughlin
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| posted on 8/1/05 at 10:47 PM |
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steve, i tried what you suggested, and there is 220 000 ohms of resistance between the end of the coil cable and the end of the spark plug cable (via
the rotor arm and dizzy cap) it seems a lot to me, as the multimeter only goes up to 1x10^6 ohms, but this may be usual.
in the coil lead itself (just the coil lead) it says there are 260 000 ohms.
i got a spark, which i was delighted to see (after bending the points inside the dizzy cap) {but i cant really see why i would have needed to do this,
as everything was running fine a few months ago}
anyway guys, time has run out, and i have to go back to uni and do exams / dissertation etc...
thanks very much for all of your help and suggestions, and ill be back asking dopey bquestions again over easter time no doubt - until then, ill just
be keeping an eye on this site more passively than actively.
thanks again,
Tom
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MikeRJ
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| posted on 9/1/05 at 02:59 PM |
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quote:
Originally posted by theconrodkid
if you got low kv then its a coil/king lead prob,all the other bits do is switch
The "other bits" make a huge difference to the secondary voltage. The induced voltage is proportional to the rate of change of current in
the primary, so if the switching circuit is faulty (whether breakers or electronic), it can greatly affect the voltage at the plugs.
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stevebubs
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| posted on 9/1/05 at 06:11 PM |
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I'd suggest taking a clloser look at the dizzy when you get back in Easter.
It only took 2 months for the points gap on my xflow dizzy to change to a point where I had trouble revving over 5k without serious misfire. When I
started messing around, the engine then wouldn't start - I'd somehow managed to blow the capacitor.
At least you've got a good starting point now.
BTW on an xflow you don't need to bend the points, you just loosen a screw and move the unit slightly to alter the gap.
This whole messing around lark was what sent me down the electronic ignition route. The only downside with that is that if something goes wrong, you
know you're *not* going to be able to fix it at the roadside!!
quote:
Originally posted by tom_loughlin
steve, i tried what you suggested, and there is 220 000 ohms of resistance between the end of the coil cable and the end of the spark plug cable (via
the rotor arm and dizzy cap) it seems a lot to me, as the multimeter only goes up to 1x10^6 ohms, but this may be usual.
in the coil lead itself (just the coil lead) it says there are 260 000 ohms.
i got a spark, which i was delighted to see (after bending the points inside the dizzy cap) {but i cant really see why i would have needed to do this,
as everything was running fine a few months ago}
anyway guys, time has run out, and i have to go back to uni and do exams / dissertation etc...
thanks very much for all of your help and suggestions, and ill be back asking dopey bquestions again over easter time no doubt - until then, ill just
be keeping an eye on this site more passively than actively.
thanks again,
Tom
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