cold start weirdness

Dan Cordon cord4530 at
Sat Jan 17 13:42:41 EST 2004

> 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

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