[alfa] V6 Spark Breakup

["Herbert Neily" <neily@xxxxxxxxxxxxxxxx>]

Hi All,

After installing rebuilt cylinder heads on my '84 GTV6, I was very
disappointed by how poorly the engine idled upon the first startup.  I
verified that my ignition and cam timing were correct.  I discovered a bad
connection at an injector's electrical lead, fixed it, and engine idled only
marginally better.  Using an inductive timing light, I found my #6 plug wire
to have a very weak and erratic signal. My plug wires were old, so I figured
it was time for a new set. I decided to replace the coil as well.

As of right now, I've got brand new:
  Spark Plugs (Bosch single electrode platinum - maybe iffy, given the
recent discussions, though my '87 Milano runs great with them)
  Distributor Cap & Rotor
  Bosch Coil
  International Auto Parts copper core wire set (their Item 23047)

The engine still idles poorly.  Tonight, I used two inductive timing lights
to check the pulses in the wires.  Plug wires #1 through #4 give distinct
and regular light pulses.  The #5 and #6 wires exhibit bright, less regular,
pulses surrounded by very quick pulses of lesser brightness.  It's as though
I've got some kind of signal leakage.  I reinstalled the old distributor cap
(which showed no cracks or carbon tracking) and rotor, only to find the
behavior the same.  I've run the car after dark and don't see any errant
sparks flying around.  To check the plugs, I swapped my #4 and #5 plugs.
The erratic signal remained in the #5 and #6 wires.

I'm at loss to explain this.  I can't imagine that the extra length of the
#5 & #6 plug wires could have any effect like this.  Does anyone have any
suggestions?  Thanks in advance.

Bert Neily
'84 GTV6  - The emissions inspection clock has stopped ticking - the alarm
is ringing now.
'87 Milano
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