Re: Wierd start problems.

[rdh@sli.com (Robert D. Houk)]

   ...
	 Well, I was puzzled at why it did this.  And, it's been doing this.  It h
   appened three more times since then (every time I've driven it since then).  It
    will start up fine when the engine is cold, but won't start up at all when it'
   s warm (i.e. within a few hours of me driving it).  I am completely puzzled, an
   d can't figure out what the problem is.  I'm also getting sick of pushing my ca
   r everywhere.  It's kind of embarrasing to be pushing you Audi :-(


Sounds to me like the proverbial "Hot Start Pulse Relay". Do you hear a
distintive "clicking" sound about every three seconds as you vainly wear
out your starter? (Assuming of course that your car is the proper vintage
to be, um, blessed with such a beastie...check your owners manual to see
if the relay diagrams show any such thing)

early/mid-80's vintage: the cold start injector is powered directly off
of the "START" circuit, and through the "thermo switch". If block is cold,
the CS injector is powered, enrichening the mixture so you start. "Hot",
the thermoswitch is open and nothing happens (except killing your battery
and engendering lots of language of which my mother would approve). The
"Hot Start Pulse Relay" is supposed to trigger the CS injector every few
seconds hot or not (by the way, I think "hot" in this context is some
fairly tepid temp like 70 to 90F, so it takes a LONG time to get cold 
enough to start again!) so that you can start the engine.

A less likely problem (although one that was **** hard to identify) is
that the ECUs are notoriously voltage-sensitive (at least the MAC-02
series). when I bought my UrQ, it had the usual butcher-job antitheft
alarm "professionally-jury-rigged" in place. Turns out there were enough
shitty crimps/etc that the voltage to the ECU was borderline. The car
would crank happily, and run happily once I got it started, but would
"occasionally" just not start at all. I finally noticed that when I
jumped it from my boringly-reliable Mitsubishi, it would always reliably
start if the Mitsu was running (i.e., supplying 14 volts), but would al-
most never start if I just jumped from a non-running battery (i.e., a
mere 12 volts . . .)! But this was cold or hot...so probably not your
problem.

					-RDH