cold start weirdness

[Dan Cordon]

> Just picking up on this thread - At least 4 of us have the same problem
> - and I've had the problem since 91 when I purchased my 87 Quattro. Only
> happens when the temperature falls below - 15 Celsius. I've tried
> absolutely everything and now just crank away until it starts (great
> starter motor!) Starts great when cold - we've been experiencing a cold
> snap - 32C - drive for anywhere from 15 minutes to 1 hour shut it off,
> when I try to re-start it cranks forever.
> Fuel pressure OK if you pull up on the air sensor plate it starts
> No air leaks
> Lots of spark
> Tried a number of CO settings - no result
> I've also thought of the CSV solution but it usually warms up before I
> get to it.
>

My 87 5k has just the opposite problem. Long starts when normal temps
outside, but super quick starts when cold. My problem seems to be leaky
injectors. When it's cold outside (anywhere from ~30° to -13°) it fires
right up, but runs slightly rough for the first second or two until the
main injectors start going.

As a test, last summer I hooked up a relay to ground the CSV whenever I
had 12V to the starter relay. Really quite simple.....using a 4-prong
relay, connect the starter signal to trigger the relay, and ground the
other three pins. It worked great for me. Started right up on warm days.

However, I pulled it off a few weeks later. I had just quickly put it
together to see if it would work, but wanted to wire it a little more
professionally. Then, the more I thought about it, I felt like "Why make
such an unprofessional hack look professional?" What I really need to do
is get new injectors. But I'm still waiting for some injector fan parts
so I don't fry the new ones on short order.

Either way, if you're okay with the hack, it seems to work fine, though
a momentary push button would be a lot quicker to instal, and give the
user more options. I tend to agree with Hue though. Get a noid light set
and diagnose what's going on with the CSV, or use a multi-meter/spark
tester to see if ignition is the real problem.

--
Dan Cordon
Mechanical Engineer - Engine Research Facility
University of Idaho