[s-cars] Cold start issue, brake fade

[Mark Rivera]

The O2 sensor looks like a new one, but I'll check again.  I'd be more
inclined to think it's a cold start system issue, so I'll check that too.
Anyone know the specs on this temp sensor so I can test?  Ahh, forget it, I
know I need to pony up and get the Bentley....

My car is missing the belly pan, so I'll keep an eye open for one of those.
Since I've refilled the PS reservoir, the "BRAKE" light stays off now.  That
sensor IS hooked up, because I had disconnected it and reconnected it when
testing that "BRAKE" light issue.

Thanks for the response.

Mark

-----Original Message-----
From: Fred Munro [mailto:munrof at sympatico.ca]
Sent: Wednesday, October 04, 2006 9:58 AM
To: Mark Rivera; S-Car-List
Subject: RE: [s-cars] Cold start issue, brake fade


Mark;

Your bogging issue may be a bad oxygen sensor. I just had the same problem
on my S6. Replacing the sensor fixed it. The old sensor was actually loose
in the manifold, so it may have had a bad ground that prevented the sensor
heater from working properly, although the car did bog a bit after shifts
even when hot. I'm still sorting through issues on the new to me S6 and I
was glad to resolve that one so easily. Your issue may also be a faulty cold
start system. The temp sensor on the back of the head sometimes fails and
disables cold start.

Does your car have a belly pan? The NACA ducts in the bottom of the pan
direct air onto the front rotors to cool them. No pan = poor front brake
cooling.

The "fade" issue may also be low boost pressure or a bad bomb. Did the brake
warning light come on? Is the low pressure sensor on the servo connected?
This can become mysteriously disconnected to "solve" warning light issues.

HTH

Fred Munro
'94 S4
'97 S6



-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Mark Rivera
Sent: October 4, 2006 9:35 AM
To: S-Car-List
Subject: [s-cars] Cold start issue, brake fade


First thing in the morning when I start my 93 S4, it wants to die.
Sometimes it does, sometimes it just stumbles badly until I blip the
throttle.  After the revs get up to about 1500, it clears up.  The only
other thing I notice when it's cold is a pretty deep bog between shifts just
after letting the clutch back in.  This carries on for the first minute or
so.  This happens when I go out for lunch as well, but the stalling only
happens when it's dead cold in the morning.  Ideas???  FWIW, the car runs
very strong when it's warm.

I flushed and bled the brakes last night, and while it firmed up the pedal a
little, it's still softer than I'd like.  I'll probably invest in some
braided lines soon.  I took the car for a spin after I was done, and tried
some heavy braking from about 80-45mph.  After about 3-4 applications like
that, the brakes were fading really bad.  My foot was almost to the floor, I
was almost out of my seat standing on the pedal, and could not get the ABS
to activate.  Matter of fact I've never had the ABS step in yet, and I
haven't locked a wheel yet either.  I cruised for about 5 minutes to cool
things down, tried again, and most of the braking had returned.  I know the
brakes are sorta weak on these cars, but I didn't know it could be this bad.
I don't wanna pony up for a caliper/rotor upgrade just yet, but would like
some pad suggestions to replace what I think are stock pads with wear
sensors.

Thanks,
Mark
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