[s-cars] Coil acting weird?

[Fred Munro]

Hi Betsey;

I have had two coil failures on my '97 S6; in fact I've just come in from
replacing the second coil. In the first failure No.5 coil went completely
dead and the car ran on 4 cylinders. It made identifying the dead coil quite
simple.
In this last failure, the No.4 coil went intermittent. The car would run on
5 cylinders, misfire for a bit, and run on 5 cylinders again. It misfired
more at idle than under power. One thing I did notice was that blipping the
throttle at idle always resulted in a stumble. 
I checked the spark plug and coil boot and swapped out the POS to eliminate
those as the problem before replacing the coil.
On my car the coil positive and ground wires are fine - it looks like the
coil was defective. I haven't road tested it yet, but it idles fine and the
stumble when the throttle is opened is gone. When you replace the coil make
sure the coil primary wires running under the plastic retainer at the end of
the coil cover are nicely lined up one beside the other. If a wire crosses
over another, the retainer will compress it and thin the insulation. This
isn't a big issue on the brown ground wires but it can cause a misfire or
even worse a crossfire on the black positive wires if the insulation thins
to the point where the wires touch.

Good luck!

Fred Munro
'97 S6


-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of Elizabeth Karnes
Sent: August 18, 2009 10:00 PM
To: s-car-list at audifans.com
Subject: [s-cars] Coil acting weird?


I have a '95 S6,  I have a coil that is working most of the time and then it
goes out for a few min making it run on 4 cylenders then it will kick back
in and run on 5.  It has been comming and going for a few days now.  I was
told that when a coil goes bad IT goes bad,  it doesn't act up.    I have
replaced 2 of them due to that same thing happening and it takes care of the
problem until it goes  to a different coil.  So any ideas on what would be
causing the coils to act up like that?

Thanks, Betsey

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