Matt,
Prod list member Joel Walker. Two or three years ago he had a very cool manual
on the Digifant fuel injection system. If you can get a copy it will help your
understanding immensely.

Keep olling the list membership. They are a good and knowledgeable bunch of
folk, and collectively probably know more than anyone else ever will about how
to keep our little beasties in tip-top shape.

Good luck,

John Rodgers
88 GL Driver
Matt Sutton wrote:

> Hi Folks,
>     First: I've only been on the list for about 10 days, and have been
> greatly enjoying it.
>     I've just ordered many parts from Bus Depot, and will do my first tune
> up when they arrive. In the mean time though, I'm wrestling with the Bently
> and trying to grasp VW logic. Here's what's been happening so far:
>     -At purchase, dash coolant gauge inoperative. Light flashes at start up,
> but still trying to establish test points and parameters with a new sender
> on the way.
>     - Seller tells me idle stabilizer valve is suspect, and ordered one for
> me.  In the meantime, I set the idle at around 900 following the Bently
> procedure as best I could (It is pretty unsteady at that RPM, though) With
> the stabilizer valve and all else reconnected, it cold-starts at 2K and
> drifts down to the RPM I'd set. Maybe the ISV is ok after all?
>     - the troubles start once it warms up. Greasy black matter coming with
> the exhaust, fumes that make my eyes burn.  I've done some highway 4th-gear
> running with it and while there's plenty of speed/power, there's also plenty
> of smoke. That part in particular gives me the willies. I pulled the oxygen
> sensor today and it was caked with soot. There is another on the way, but
> I'm afraid of destroying it. Fuel economy is very poor.
>     -the good news: as far as I can tell, it is retaining coolant and oil.
> It also starts like a dream.
>     Maybe I should say this, too: My last car was a 78 ford fairmount, truly
> amazing vehicle that I kept running for 12 years, and this new fangled fuel
> injection is mystifying me.  Is the ECU you all speak of the same thing as
> the "Digifant Control unit" which seems to have sensors in every part of the
> engine? Am I right in thinking that if any one of those sensors goes, or
> provides misleading info, performance goes down the tubes?
>     You can see where I'm going with this, perhaps.  I am willing to put the
> time in, but need it to count for something besides character building.  Is
> there anything I can do before the tune up that will make the tune-up worth
> it?
>     New cap, rotor, plugs, cables. New airfilter, oil change (20w/50) with
> filter. These will happen in one fell swoop, hopefully. Should I make sure
> the coolant temp sender is straightened out first? Should I replace the
> oxygen sensor after I'm on the right track, to keep from destroying a very
> expensive part?
>     Thanks to all who responded to my initial inquiry, and to any who can
> provide ideas, mind-set adjustments, etc., in response to this one.
>                                         -Matt Sutton