Fw: cold start weirdness

[SJ]

From: "Huw Powell" <audi at humanspeakers.com>


> > Three of us have similar problem - temp no start when cold, or after 10
min
> > warmup.
> > What do you think of the [CSV] switch idea?
>
> Sounds like a waste of energy to me.  It is as much trouble
**** I thought it might be some trouble to wire up. But, actually, its
simpler than I thought. The cold start valve always has 12 volts on it - G/R
wire. The ECU grounds the BR wire to fire the injector.
All that is needed is a simpler 2 wire (off-on) pushbutton switch. Splice
one switch contact to the BRN wire, and wire other switch contact to ground.
Thats it.

>as
> diagnosing the CSV system and fixing it if it is not working right, and
> of course, it doesn't fix anything, it's just a hack, really.
**** The only thing it will fix is getting your engine started when you are
stuck at the supermarket. My idea was to provide a simple method of proving
that it is indeed a fuel related problem, in particular ECU/temperature/cold
start injection related.
When stuck in a supermarket parking lot, freezing my nuts off, and with no
tools or test equipment to play with . . that pushbutton switch idea dont
sound too bad.
This would just be a temporary measure to prove an assumption, and eliminate
the ignition system.

> I don't mind having a manual choke on my '73 F250 beast.  I wouldn't
> want one on a fuel injected Audi.
**** My 85 Dodge D250 must be having sympathy pains. I'm ready to put in a
manual choke kit. The auto choke works fine when its above 32 F. Any colder
and it opens up too soon, and the engine dies.

> Troubleshooting the CSV system is pretty simple, really, since there are
> only one or two parts.
**** Its not so simple when the problem occurs whenever it wants to, and
goes away just as quickly. There are three of us now that have a similar
problem. And no solution in sight.
I have replaced the temperature sensor since that appeared to be the most
logical candidate. I test the car almost every day. So far, so good.
I do have a niggling suspicion that the problem might be related to a
specific temperature range around 30 F. This is the temperature when the
problem always showed up. Maybe something to do with metal contraction .
.like connector contacts.

>
> On my 90 I am also highly suspicious of air leaks, say around the ISV
> hose ends.  I just replaced a flaky IM top half bolt in case there was a
> small leak there.
>
> When it's very cold, a small air leak could make the engine too lean to
> start.  Especially if it is a bigger leak when very cold.
**** If it was an air leak, why doesnt it do it every time its cold? That
simple pushbutton switch would quickly eliminate this possibility.
When it dont start, hit the button. If it now starts, its lean. If it dont
start, its ignition.

Maybe we can get this thread as long lasting and convoluted as the
torque/extension tool thread. Hey, we gotta do something on these cold
nights.

SJ