[s-cars] B6 doesn't turn over in the cold.

[Sean Reifschneider]

I have a 2005.0 S4 and since the temperature has turned cold it has
started being hard to start.  Everything works as normal except the
starter doesn't engage for half a second to 30 seconds or longer (one
time I tried for 10 minutes).  The lights all come on when I turn the
switch as normal, but it just won't fire the starter.

As the weather started getting colder, I started noticing it take half
a second after I turned to start, where before it was instant.  As it
got colder it progressively got worse.

Usually after I drive it and leave it sitting an hour to 4 hours I have
little if any trouble starting it.  But after it sits over night it can
be hard to start.

The one time that it didn't start at all, I put a kilowatt heater blowing
under the car by the front drivers side wheel for an hour, and then it
started right up.

Here is what I've done for diagnostics:

    Replaced the battery.  This was because once under acceleration the
    battery light went on, and it's 5 years old so I figured I might as
    well.

    I have tried another key with the same results, just in case the
    immobilizer in the original key was having issues.

    A little bit of heat blowing into the engine compartment behind the
    front drivers side tire seems to help a lot.

    Took it to my independant shop but they were confounded.

    It *MIGHT* work better if I turn the key SLOWLY from "on" to "start",
    but sometimes it doesn't.

    When I press the clutch pedal I can hear what sounds like a relay
    activating or deactivating as I press and release around 80% of the way
    in.

    The drivers side mat is firmly planted on it's pins, and pressing the
    clutch pedal slightly hard doesn't help.

I'm thinking it's something related to the clutch interlock because:

    Blowing some heat into the engine compartment for 15 to 60 minutes seems
    to greatly help.

    If it were the starter, I would expect it to need heat much longer to
    warm up.  I'm blowing the heat in fairly close to where the clutch is,
    though I admit I don't know exactly where the starter is, they're pretty
    weighty and I wouldn't expect even an hour of heat blowing in would make
    a whole lot of change to the temperature of the starter.

    The ignition key isn't getting any heat from this heater, as it's
    blowing under the car, not inside it.

I'm expecting that the problem is isolated to the starter, ignition switch,
or clutch switch.  Or maybe the ECU (Ugh).

Any advice before I take it in to the dealer?  I'm not really looking
forward to trying to isolate the issue in the snow, but think it should be
a fairly simple check of voltage at the starter to see if it's getting the
voltage and not firing, or not, in which case then check the clutch and
ignition inputs.  Immobilizer complicates the ignition switch I imagine.

Thanks,
Sean