[s-cars] Clutch pedal and more

[Tim Moore]

Hi everyone,

I'm calling from England re my recently purchased 93 S4 Avant. Apart from
being the best combination of quality, practicality and performance I've
ever had, there are a few issues I'd appreciate some help with:

1 The clutch pedal has decided to drop to half its normal height and only
semi-disengage the clutch, making the car undriveable.. I've bled the
hydraulics but it's still there and, if anything, is worse. If you put your
toe under it and heave it up it returns to its normal position, but on
depressing it again and peering under the dash whilst doing so you can see
the fluid pipe bending as the pedal moves. The whole thing is moving in its
mounting. Is this a regular issue with this car? How much trim do I have to
remove to get at it?

2 The engine pulls well and shows no signs of undue wear but there's a
misfire which manifests itself in the following ways:

You're driving normally (!) with a light right foot and suddenly the engine
will cut out momentarily, snatching the transmission violently.

You're in 3rd. You floor the accelerator and the thing misfires constantly
on 2 or 3 cylinders. If you slowly back off the power there comes a point
where everything kicks in again.

Sometimes, not everytime, after a run of 20-30 miles it will just die at
idle. Starts again fine.

Could it be as simple as plugs? I've changed the oil already but that's as
far as I've got with servicing. Will a K&N air filter improve performance?
Will I get bugs and grit in the turbo? Chad Tobin suggested the fault might
be in the power output stage(s) but I haven't found a way to test them yet
as the fault is intermittent.

3 And finally. I decided, after visiting SJM Autotechnik's great site
(thanks again Chad), to run a fault code diagnosis and ascertain whether the
misfire was due to a component that had 'registered a complaint' with the
ECU. I made up a test light, plugged it in, inserted the jumper cable
and...2.5 seconds on...off...then nothing. Tested the +12v and ground
connections. Fine. Pulled the fuse on the ECU to erase the fault code memory
and took it for a spin, flooring it in 3rd as requested (exhilarating apart
from the misfire). Tested again. Same result. Any ideas? Surely if there's
nothing wrong it should blink 4-4-4-4.

Would appreciate any ideas you may have.

Regards,

Tim Moore