[V8] very little audi content

[dsaad at icehouse.net]

I had an Audi (4000 S) that had CIS fuel injection.  There is the
content...

I have been trying to get my sons new to him 1989
Merc 190E 2.6L up to snuff and that means diving headfirst into the CIS
guts of this machine. WOW.  this is one complex system that is
guarenteed to fail due to the huge number of microswitches,
potentiometers, vacuum lines, and bla bla bla.

To finally get
it working smothly I had to dissamble a goofy thing called the
"Overvoltage Protection Relay" and scrape/clean the relay
contacts. This ingenius device causes all sorts of seemingly unrelated
things to happen.  Next was the air flow meter potentiometer. 
It was givving very eratic readings and apparently new ones are crazy
expensive as well as no longer available.  I ended up fixing this one
by drawing over the carbon trace with a big fat graphite pencil to give it
better conductivity. After that, it is starting easy and running
smooth.  Time will tell how long it lasts but at least now I know
what to repair it.
In the process I managed to break off a rubber
hose fitting on the fuel pressure regulator - which I think is just a vent
so not too big a deal but like my Audi, all the underhood rubber and
plastic vacuum bits disintegrate if you look at them too long.

And finally, at idle with the AC on, there is a rattle comming from what
I guess is the cam sprocket area.  Anyone know if this is a sign of a
sloppy timing chain or tensioner?  Should I just leave it alone?

Dave