[s-cars] Bad POS?

[Paul Gailus]

Jerry brings up a good point about the coil grounds.
One way a coil can fail is if the ground return of the
secondary winding gets disconnected. Then the secondary
voltage can arc to the primary winding, leading to eventual
failure. On a spare Beru replacement coil that I have, the
bare ground return wire is spot welded to the iron core.
I assume that the OEM coil is similar. If this weld pops,
or if the core is not tied well to ground, then the failure
mode mentioned above is a possible outcome.

Paul

----- Original Message -----
From: Jerry Scott <jerryscott at earthlink.net>
To: The Gagnons <bullitt at gwi.net>; s-car-list <s-car-list at audifans.com>
Sent: Monday, February 16, 2004 12:56 AM
Subject: Re: [s-cars] Bad POS?


> Before you go blaming the POS try this, as it worked for me.  Remove the
> coil cover. Remove each coil and clean the white ash deposit that build
> up on the grounded coils, under the four bolts.  Also clean the single
> ground lead that attaches near the back of the cover.  If this does not
> fix the misfire, change the rubber plug boot for that cylinder.
> Jerry
>
> The Gagnons wrote:
>
> >Hello,
> >
> >I was driving my wife's 92 S4 today and noticed that it developed a bad
> >misfire while going through Portland, ME on Rt 295 at about 60 mph.  The
> >misfire only lasted about a 1/2 mile and then went away.  After a quick
stop
> >at LL Bean, the car started misfiring from the get-go.  We stopped at
Mickie
> >D's ( just around the corner) for some food for my son and I was able to
> >determine that it was the #3 cylinder that was misfiring by pulling the
> >injector leads one at a time.  I suspected the POS so I checked the
> >connections and it came out of it as soon as I restarted the car.  We
> >continued to Bath (about 15 miles north) to visit some friends and upon
> >restarting it was misfiring again.  We drove about 3 miles this way and
it
> >again stopped misfiring and was fine all the way home (about 60 miles).
> >
> >When I got home, I looked up the POS write up on SMJ's website and
> >determined that I was lucky enough to have the # 3 channel go bad and
> >swapping the right POS with the left would put the bad channel to the
unused
> >position.
> >
> >I really hope that is all It was, but am not sure.  My wife is driving
200
> >miles to MA and back on Tuesday and would like to know if there is any
other
> >possibilities before sending her on her way.
> >
> >Any Ideas or feedback?
> >
> >Thanks
> >
> >Jack