[alfa] V6 Spark Breakup - Solved! (Long)

["Herbert Neily" <neily@xxxxxxxxxxxxxxxx>]

Hi All,

Many thanks to all who responded to my questions about my GTV6's spark
breakup.

I think I solved my problem.  This afternoon, after diddling around some
more with the car, I finally decided to get back to the really simple stuff.
My signal breakup had always been isolated to the left side of the engine
(the #4, #5 & #6 wires, mostly #4 & #5).  I pondered the fact that I always
had *two* wires with a problem at any given time.  I looked at the wire set
and wondered about the fact that the three left-side wires and the coil wire
were bundled together by a short sheath of plastic at about the centerline
of the engine.  The right side wires weren't similarly bundled.  I got some
scissors, cut the sheath, and rerouted the #4 & #5 wires over the top of the
intake plenum (just like I'd routed my old #4 & #5 wires when they worked
successfully).  Bingo! - the miss went away and the timing light showed
regular pulses in all wires.  I rerouted the wires to a more permanent
arrangement, keeping them separated, and the car runs fine.

I can only assume that both new wire sets has the same apparent cross-wire
signal leakage where the left-side wires were bundled.  The plastic sheath
appeared intended as a permanent element.  I can't say that I'm very pleased
with the marginal performance of the brand new wire insulation.  I can't
imagine that they won't deteriorate further with the passage of time and
repeated bakings under the hood.  So, I'm inclined to return both wire sets
and seek a higher quality wire set.  A couple of weeks ago, someone else
posted a request for suggestions of a good manufacturer and supplier of
quality wires for the V6.  I don't recall seeing any suggestions, but I'd
sure like to see one now.  Anyone?

In the course of troubleshooting this thing, I've about worn out my
ohm-meter.  After checking the resistance of a number of different ignition
components (in some cases multiple examples of the same components), I'm
left completely confused by the results.   Bear with me here.....

I checked the resistance between the inside contacts and the external wire
seats on each of the three caps that I have (two Italian "Facet" caps and
one Mexican-made "Dana-Echlin" caps, each supposedly "correct" for the
GTV6).  None of the caps had a wire location that measured more than 1.5
Ohms (that's Ohms, not kOhms).  I studied the caps and can't see any
indication of integral resistors.  So, it looks like these caps have no
built-in resistance.

My two Facet rotors measure 1.1 kOhms.  The Dana-Echlin rotor is a solid
copper bar from the center to the tip, so its resistance is virtually zero.
The Bosch rotor on my Milano measures 5.0 kOhms.

I tried to measure the resistance of the Bosch Platinum single
side-electrode plugs themselves, but the small gap wouldn't let me get my
ohm-meter probe in contact with the tiny platinum center electrode.  I was
more successful with an old Bosch Platinum Plus 4 plug - it measured 3.4
kOhms.  The brand new NGK BP6ES plugs, that I bought today, measured only
about 1 Ohm - virtually no resistance.

My two new copper-core wire sets measure 2.4 kOhms.  My old fiberglass-core
wires measured anywhere from 5.9 kOhms to 11.8 kOhms, depending on the wire
length.

In consideration of all that, my question is this - just what in the hell
are the CORRECT OFFICIAL resistances for these various components (or the
total correct resistance measured from the inside of the distributor cap to
the center electrode of the plug)?  The values vary all over the map - all
with supposedly correct parts.  The car is presently running fine with the
separated 2.4 kOhm copper-core wires, the 1.1 kOhm rotor, and the zero
resistance NGK plugs.  Now I wonder how long it will be before the system
melts down.  If the total resistance really matters (it seems that it
should), then I'm surprised that the various parts vendors and the Alfa shop
manuals are not more explicit regarding all of this.

Thanks again to everyone.

Bert Neily
'84 GTV6 finally ready for emission inspection
'87 Milano donor - "Leave me alone!"
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