Subject: S4 Hiccough. HELP!

[C1J1Miller@aol.com]

Gary wrote:
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Just purchased a 92 S4 with 68k.  On the ride home from DC to Portland
ME, I experienced what can best be described as a hiccough. For a
fraction of a second it seemed like somebody flipped the run switch off
then quickly back on.  First time it happened twice within two minutes.
Second time it happened once.  Third time it happened twice.  Then I
drove 5 hours without a repeat.  Maybe a fuel pump relay?  Any
diagnostic ideas welcome.  It is the kind of intermittent thing that
would never happen when you want it to.
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Congrats, nice car.  The S4/S6 uses a Motronic ECU (brain) that can store
faults/trouble codes in either volatile or permanent memory, dependant on type
of fault and frequency of occurance.  You can build a jumper/LED wire and
connect it to the diagnostic connector, and the brain will blink out a series
of four-digit blink codes.  The procedure to make such a jumper/LED is on my
web site under repairs/engine.  The procedure is for the '91 200q which has a
similar version of the motronic brain.  After driving and getting the
intermittant fault, and before shutting down the engine, hook up the jumper
and LED, and start the code dump procedure.  This is a good basic starting
point.  If no trouble codes are found, it's time to balance the "fix it
yourself" vs. the "pay a mechanic to experiment" costs.  I'd recommend getting
the Audi Factory Service Manual, produced by Robert Bentley (Bentley manual),
as I recall it includes the 100 models as well.  

Otherwise, bring the car to a dealer or better yet independant audi specialist
and they can hook up the VAG 1551 and read the codes directly.
HTH, and I have no experience with using the above on the S4/S6 (but it works
great on my '91 200q)
Chris Miller, Windham NH, c1j1miller@aol.com
http://members.aol.com/c1j1miller/index.html
Also see Scott Mockry's site (linked from my site) for further diagnostic
information, again for the '91 200q, but should apply as well to the S4/S6.
Also, check the audi-s-cars.com site.