[s-cars] 93' S4 - Hard Starting

[calvinlc at earthlink.net]

Bruce,

I had a similar experience on my S4.  Tried fuel pump relays and all sorts
of junk.  It was intermittent as well.  Next time it happens and you can't
start it right away just turn the ignition key off, then on again for about
3 seconds.  Repeat this about 10 times.  Try to crank it up after this
procedure.  If it cranks right away it is either your fuel pump check valve
or, as was my case, the fuel pressure regulator.  One thought on the TPS, it
could be that the TPS is indicating that it is basically all the way to the
floor which may cause extra gas on startup.  Maybe Mihnea or somebody who
better knows the Audi software could tell us whether or not the TPS has
anything to do with startup.

--Calvin


-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Mock, Bruce J
(Bruce)
Sent: Tuesday, January 11, 2005 4:31 PM
To: s-car-list at audifans.com
Subject: [s-cars] 93' S4 - Hard Starting


Hey Guys!  Looking for the groups collective wisdom here:

'93 S4 170,000 mi...exactly.

Car is hard to start - Sometimes - not all the time - hot engine or cold
doesn't seem to matter - I have to crank and crank before she will run.
Other times she starts right up.  After a day and a half of this behavior, I
did finally get a check engine light.  So... I went down to my favorite
Denver area Mechanic/tuner, Champagne Motors, and had them pull codes.  Code
for the Throttle. Pos. Sensor came up.  Hmmm.  We cleared that code with the
hope that it would come back after a few motor starts, stops and driving.
It did not.  TPS code makes no sense to me since we know that you can
disconnect the TPS and the car will start without it!

My initial thought, based upon years of soaking up all of this great list
wisdom was a bad Cam Position Sensor.  But doesn't a bad/flaky CPS usually
set a code in the computer??  Also, the CPS is a bear to get to and is an
expensive part - so hate to go blindly replacing this thing.

Champagne's thought was that this behavior might be due to a
bad/intermittent fuel pump check valve.  But, this only makes sense if after
a long rest (cold motor) e.g. - that you would need to crank for a long time
to get fuel back into the system.  This AM, after a long cold night's rest,
the car started right up!  That shoots the bad check valve theory, right?

At this point I'm at a loss...  So I'm just driving the car and living with
the hard starts!

Interestingly, this all happened EXACTLY as the odo turned over to
170,zero,zero,zero miles.  Talk about planned obsolescence!

Bruce in Denver



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