Date: Tue, 14 Sep 2004 13:19:17 -0500
Reply-To: Aerowolf <aerowolf@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Aerowolf <aerowolf@GMAIL.COM>
Subject: Re: testing the ignition coil (85 1.9L)
In-Reply-To: <vanagon%2004091319275679@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=US-ASCII
Thanks for the help!
Would it work to just ground the old plug's side electrode, instead of
knocking the electrode off entirely? That way, the gap could be kept
at the 0.028" to 0.031" that the book recommends? Or should the gap
be a bit wider than the normal plugs to test for actual coil voltage?
(I went a bit overboard and bought a battery ground cable to ground
the engine to the body under the ignition relay panel -- the old strap
that had been there wasn't there, and I wanted to ensure I had a good
ground. so I'm pretty sure that grounding isn't an issue here.)
In the event that the + and - both show a steady voltage, which other
parts might I have to worry about? How difficult is it to replace a
Hall Effect Generator inside the distributor, if it comes to it? (or
should I just give up and buy a new distributor, since that's a lot
easier to install than rebuilding an old one?) How could I verify
that it's that, and not the ignition control unit?
Also, here's a part of my lack of training showing through: On the
crankshaft, if the timing mark is at TDC, does that mean that the #1
cylinder is at TDC? Or does it have a multiplier such that it could
be one of 2 or 4 cylinders at TDC? In the latter case, how would I
tell when it's on #1? (please forgive my ignorance here -- I'm asking
because if I have to replace the distributor, I need it to be at TDC
cylinder 1.)
-Kyle
On Mon, 13 Sep 2004 19:26:51 -0400, Daniel L. Katz <katzd54@yahoo.com> wrote:
> kyle:
>
> a bad coil is truly rare.
>
> first get an old spark plug and break off the side electrode to make a
> tester. then pull off one spark plug wire at the plug and insert tester,
> with the center electrode a few mm from a convenient ground (engine or
> body). have an assistant crank and look for a spark. if no spark, pull off
> coil wire at distributor and again crank and look for a spark a few mm to
> ground. if no spark, and assuming coil wire is ok, then go on to the coil.
> your test light should have a wire with an allegator clip, which you clip
> to any clean unpainted ground (body or engine) to complete the circuit.
> with an assistant cranking, test light should turn on more or less steady
> when touching coil (+); if not, no voltage at coil (+), which has nothing
> to do with the coil. assuming voltage at coil (+), light should flicker
> when touching coil (-) while cranking; if no light, coil primary is open
> (bad coil); if steady light, other ignition parts at fault. while
> cranking, voltage at coil (-) normally spikes to about -300 V, which will
> really bite if you close the circuit with your body. if tests at coil +/-
> check out ok, then, since no spark, coil secondary probably shorted (bad
> coil).
>
> it is hard on ignition module to make spark jump more than a few mm, or
> worse, leave high tension side open, so either re-attach plug and coil
> wires or ground them once you've tested for a spark.
>
> it is possible to have spark voltage on coil wire but no spark at plug
> because of moisture inside cap.
>
> this is pretty brief, but outlines what to do to test coil without a
> meter.
>
> as i said, almost all coil replacements are unnecessary - due to a
> mistaken diagnosis, or just plain wrong guessing.
>
> dan
>
>
>
> On Mon, 13 Sep 2004 09:40:54 -0500, Aerowolf <aerowolf@GMAIL.COM> wrote:
>
> >Heya, in my continued travails of getting Morgan running again (it
> >lost spark on the highway), I have found that people seem to suggest
> >that there's only a few pieces that can fail, with the coil being the
> >most likely. One of my friends has suggested that putting a test
> >light on the coil contacts would be a good idea, to make sure that the
> >ignition control unit is doing its proper job. (his suggestion is
> >that if the light flashes while I'm cranking it, the ICU's doing its
> >job, and the coil isn't.)
> >
> >My question is, "where would I put the test light contacts?" There
> >are three contacts on the coil, one of which is the
> >high-voltage-to-the-distributor, one is two-green-wires (marked "-1"),
> >and the other is three individual black and black/white wires (marked
> >"15+").
> >
> >Assuming I'm reading this right, the 15 terminal would be where I push
> >the probe, and I would connect the clip to ground? I don't want to
> >damage my ignition system, and since I'm not the best electrician on
> >the planet, I'd like to make sure that my assumptions are correct.
> >
> >Any suggestions? Thanks!
> >
> >-Kyle
>
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