[s-cars] Coil solutions

[JC]

>
> You forgot option 4) Re-wiring.

> POS to the coils are nothing special. They carry low voltage,
> not high voltage like single bobbin ignition systems. Any

agree entirely with Vincent's remarks except to add that the wires DO carry
decent current (the POS's are basically a power amp made via a triple
darlington array of transistors that turn the ECU control signal into enough
power, then the coil turns the current into high voltage to get the zap).
but that still doesn't mean anything so special - as he says just replace
with high quality stranded copper of same or better gauge as OEM.  (we can
let aviation guys start quibbling about the benefits and perils of soldering
vs. crimping...)

I'm facing the same issue of cracked insulation in my car.  I'm thinking 1/2
of the guys who do coil jobs may just have intermittent shorts/opens in the
wiring loom that could be brought back to life.  coils are merely simple
transformers, the OEM ones are really robust in construction, and a decently
made transformer has a huge service life as long as you don't crank voltage
into it with an open secondary and/or otherwise expose it to temp extremes
that compromise the winding insulation.  a primary side short or open -
which is what the wiring loom problems are - should not endager them at all
(although a short would very much stress the POS...), so I have VERY big
doubts that many of the coil CORES fail (although admittedly there could be
an engine heat over time factor)

especially with the proven tendency for the supply wires to crack their
insulation, I'm look much more to wiring problems as the failure-mode for
coil-packs AND perhaps even to explain the POS burn-outs.

I've even considered home-brewing POS's, although you'd be hard pressed to
get the efficient form-factor of the OEM IC.  Bosch semi-conductor division
sells single triple-darlington IC's in discrete packaging for exactly this
application so it looks imminently doable.  however with the GM units out
there it's hard to get too wound up about that as a project...

---- current ----
1995.5 S6 Avant
---- past lives ----
2006 A4 2.0TQA
1998 A6Q 2.8 PES G2
1989 200TQA SJM
1990 CQ
1997 A4 1.8TQ Wett
1987 4kCSQ

John J. Cunningham
jc at j2c3.com
US Mobile +1 (617) 750-5025
Main / Global +1 (978) 633-3510
China Mobile: +86 (0) 136 6080 9560


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